JP2020054982A - Catalyst for exhaust gas purification - Google Patents
Catalyst for exhaust gas purification Download PDFInfo
- Publication number
- JP2020054982A JP2020054982A JP2018189365A JP2018189365A JP2020054982A JP 2020054982 A JP2020054982 A JP 2020054982A JP 2018189365 A JP2018189365 A JP 2018189365A JP 2018189365 A JP2018189365 A JP 2018189365A JP 2020054982 A JP2020054982 A JP 2020054982A
- Authority
- JP
- Japan
- Prior art keywords
- earth metal
- alkaline earth
- exhaust gas
- catalyst
- gas purifying
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000003054 catalyst Substances 0.000 title claims abstract description 185
- 238000000746 purification Methods 0.000 title abstract description 31
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims abstract description 129
- 238000004453 electron probe microanalysis Methods 0.000 claims abstract description 22
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims abstract description 20
- 238000005211 surface analysis Methods 0.000 claims abstract description 20
- 150000001342 alkaline earth metals Chemical class 0.000 claims description 111
- 239000000463 material Substances 0.000 claims description 63
- 239000002245 particle Substances 0.000 claims description 41
- 239000000843 powder Substances 0.000 claims description 41
- 229910052788 barium Inorganic materials 0.000 claims description 24
- 239000002002 slurry Substances 0.000 claims description 24
- 239000000725 suspension Substances 0.000 claims description 24
- 239000002994 raw material Substances 0.000 claims description 23
- 150000002484 inorganic compounds Chemical class 0.000 claims description 18
- 229910010272 inorganic material Inorganic materials 0.000 claims description 18
- 229910052751 metal Inorganic materials 0.000 claims description 18
- 239000002184 metal Substances 0.000 claims description 18
- -1 alkaline earth metal sulfate Chemical class 0.000 claims description 17
- 239000000758 substrate Substances 0.000 claims description 17
- 150000002894 organic compounds Chemical class 0.000 claims description 16
- 150000001875 compounds Chemical class 0.000 claims description 15
- 238000004519 manufacturing process Methods 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 15
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 claims description 13
- 238000002485 combustion reaction Methods 0.000 claims description 11
- 238000010304 firing Methods 0.000 claims description 10
- 238000001035 drying Methods 0.000 claims description 9
- 239000003125 aqueous solvent Substances 0.000 claims description 8
- 239000002243 precursor Substances 0.000 claims description 7
- 229910052712 strontium Inorganic materials 0.000 claims description 7
- 238000002441 X-ray diffraction Methods 0.000 claims description 5
- 239000000126 substance Substances 0.000 claims description 5
- 229910052791 calcium Inorganic materials 0.000 claims description 4
- 125000000524 functional group Chemical group 0.000 claims description 4
- 238000000151 deposition Methods 0.000 claims description 3
- 125000000475 sulfinyl group Chemical group [*:2]S([*:1])=O 0.000 claims description 3
- 125000000020 sulfo group Chemical group O=S(=O)([*])O[H] 0.000 claims description 3
- 125000000472 sulfonyl group Chemical group *S(*)(=O)=O 0.000 claims description 3
- IOVCWXUNBOPUCH-UHFFFAOYSA-M Nitrite anion Chemical compound [O-]N=O IOVCWXUNBOPUCH-UHFFFAOYSA-M 0.000 claims description 2
- 239000000470 constituent Substances 0.000 claims description 2
- XMBWDFGMSWQBCA-UHFFFAOYSA-N hydrogen iodide Chemical compound I XMBWDFGMSWQBCA-UHFFFAOYSA-N 0.000 claims description 2
- 239000004615 ingredient Substances 0.000 claims 1
- 238000005259 measurement Methods 0.000 abstract description 18
- 239000006185 dispersion Substances 0.000 abstract description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 113
- 239000010410 layer Substances 0.000 description 100
- 239000007789 gas Substances 0.000 description 81
- 239000010948 rhodium Substances 0.000 description 26
- 229930195733 hydrocarbon Natural products 0.000 description 23
- 150000002430 hydrocarbons Chemical class 0.000 description 23
- 230000000052 comparative effect Effects 0.000 description 17
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 16
- XOAAWQZATWQOTB-UHFFFAOYSA-N taurine Chemical compound NCCS(O)(=O)=O XOAAWQZATWQOTB-UHFFFAOYSA-N 0.000 description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 15
- 239000002585 base Substances 0.000 description 14
- 229910052697 platinum Inorganic materials 0.000 description 13
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 11
- 230000000694 effects Effects 0.000 description 10
- 238000012360 testing method Methods 0.000 description 10
- 239000002131 composite material Substances 0.000 description 9
- 239000011148 porous material Substances 0.000 description 8
- 230000008569 process Effects 0.000 description 8
- 239000011163 secondary particle Substances 0.000 description 8
- 229960003080 taurine Drugs 0.000 description 8
- 238000013507 mapping Methods 0.000 description 7
- 231100000572 poisoning Toxicity 0.000 description 7
- 230000000607 poisoning effect Effects 0.000 description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 6
- 239000000523 sample Substances 0.000 description 6
- 238000004458 analytical method Methods 0.000 description 5
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 5
- 239000011230 binding agent Substances 0.000 description 4
- 239000011575 calcium Substances 0.000 description 4
- XVOYSCVBGLVSOL-UHFFFAOYSA-N cysteic acid Chemical compound OC(=O)C(N)CS(O)(=O)=O XVOYSCVBGLVSOL-UHFFFAOYSA-N 0.000 description 4
- 238000011068 loading method Methods 0.000 description 4
- 238000005192 partition Methods 0.000 description 4
- 238000011144 upstream manufacturing Methods 0.000 description 4
- QMMFVYPAHWMCMS-UHFFFAOYSA-N Dimethyl sulfide Chemical compound CSC QMMFVYPAHWMCMS-UHFFFAOYSA-N 0.000 description 3
- 230000001133 acceleration Effects 0.000 description 3
- 150000001242 acetic acid derivatives Chemical class 0.000 description 3
- ITHZDDVSAWDQPZ-UHFFFAOYSA-L barium acetate Chemical compound [Ba+2].CC([O-])=O.CC([O-])=O ITHZDDVSAWDQPZ-UHFFFAOYSA-L 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 150000002826 nitrites Chemical class 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 230000001376 precipitating effect Effects 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 238000010298 pulverizing process Methods 0.000 description 3
- 238000006722 reduction reaction Methods 0.000 description 3
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 3
- ZAJAQTYSTDTMCU-UHFFFAOYSA-N 3-aminobenzenesulfonic acid Chemical compound NC1=CC=CC(S(O)(=O)=O)=C1 ZAJAQTYSTDTMCU-UHFFFAOYSA-N 0.000 description 2
- RXCMFQDTWCCLBL-UHFFFAOYSA-N 4-amino-3-hydroxynaphthalene-1-sulfonic acid Chemical compound C1=CC=C2C(N)=C(O)C=C(S(O)(=O)=O)C2=C1 RXCMFQDTWCCLBL-UHFFFAOYSA-N 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
- YWHLKYXPLRWGSE-UHFFFAOYSA-N Dimethyl trisulfide Chemical compound CSSSC YWHLKYXPLRWGSE-UHFFFAOYSA-N 0.000 description 2
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 description 2
- LEVWYRKDKASIDU-IMJSIDKUSA-N L-cystine Chemical compound [O-]C(=O)[C@@H]([NH3+])CSSC[C@H]([NH3+])C([O-])=O LEVWYRKDKASIDU-IMJSIDKUSA-N 0.000 description 2
- FFEARJCKVFRZRR-BYPYZUCNSA-N L-methionine Chemical compound CSCC[C@H](N)C(O)=O FFEARJCKVFRZRR-BYPYZUCNSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 125000003277 amino group Chemical group 0.000 description 2
- OBESRABRARNZJB-UHFFFAOYSA-N aminomethanesulfonic acid Chemical compound NCS(O)(=O)=O OBESRABRARNZJB-UHFFFAOYSA-N 0.000 description 2
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 2
- 229910052921 ammonium sulfate Inorganic materials 0.000 description 2
- 235000011130 ammonium sulphate Nutrition 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 229910002091 carbon monoxide Inorganic materials 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 2
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 229910052878 cordierite Inorganic materials 0.000 description 2
- 229960003067 cystine Drugs 0.000 description 2
- PFRGXCVKLLPLIP-UHFFFAOYSA-N diallyl disulfide Chemical compound C=CCSSCC=C PFRGXCVKLLPLIP-UHFFFAOYSA-N 0.000 description 2
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 description 2
- ALVPFGSHPUPROW-UHFFFAOYSA-N dipropyl disulfide Chemical compound CCCSSCCC ALVPFGSHPUPROW-UHFFFAOYSA-N 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000010894 electron beam technology Methods 0.000 description 2
- 238000010828 elution Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 150000004694 iodide salts Chemical class 0.000 description 2
- 229930182817 methionine Natural products 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 239000008188 pellet Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 229910052703 rhodium Inorganic materials 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000002356 single layer Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- UBXAKNTVXQMEAG-UHFFFAOYSA-L strontium sulfate Chemical compound [Sr+2].[O-]S([O-])(=O)=O UBXAKNTVXQMEAG-UHFFFAOYSA-L 0.000 description 2
- HHVIBTZHLRERCL-UHFFFAOYSA-N sulfonyldimethane Chemical compound CS(C)(=O)=O HHVIBTZHLRERCL-UHFFFAOYSA-N 0.000 description 2
- 239000011800 void material Substances 0.000 description 2
- DGVVWUTYPXICAM-UHFFFAOYSA-N β‐Mercaptoethanol Chemical compound OCCS DGVVWUTYPXICAM-UHFFFAOYSA-N 0.000 description 2
- ZFFTZDQKIXPDAF-UHFFFAOYSA-N 2-Furanmethanethiol Chemical compound SCC1=CC=CO1 ZFFTZDQKIXPDAF-UHFFFAOYSA-N 0.000 description 1
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- 238000004438 BET method Methods 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- 229910021536 Zeolite Inorganic materials 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 150000001341 alkaline earth metal compounds Chemical class 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- IXSUHTFXKKBBJP-UHFFFAOYSA-L azanide;platinum(2+);dinitrite Chemical compound [NH2-].[NH2-].[Pt+2].[O-]N=O.[O-]N=O IXSUHTFXKKBBJP-UHFFFAOYSA-L 0.000 description 1
- SGUXGJPBTNFBAD-UHFFFAOYSA-L barium iodide Chemical compound [I-].[I-].[Ba+2] SGUXGJPBTNFBAD-UHFFFAOYSA-L 0.000 description 1
- 229940075444 barium iodide Drugs 0.000 description 1
- 229910001638 barium iodide Inorganic materials 0.000 description 1
- GJTDJAPHKDIQIQ-UHFFFAOYSA-L barium(2+);dinitrite Chemical compound [Ba+2].[O-]N=O.[O-]N=O GJTDJAPHKDIQIQ-UHFFFAOYSA-L 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 229910000420 cerium oxide Inorganic materials 0.000 description 1
- 239000003426 co-catalyst Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000013480 data collection Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 230000002939 deleterious effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- VAYGXNSJCAHWJZ-UHFFFAOYSA-N dimethyl sulfate Chemical compound COS(=O)(=O)OC VAYGXNSJCAHWJZ-UHFFFAOYSA-N 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- LTYMSROWYAPPGB-UHFFFAOYSA-N diphenyl sulfide Chemical compound C=1C=CC=CC=1SC1=CC=CC=C1 LTYMSROWYAPPGB-UHFFFAOYSA-N 0.000 description 1
- 238000007922 dissolution test Methods 0.000 description 1
- VHJLVAABSRFDPM-QWWZWVQMSA-N dithiothreitol Chemical compound SC[C@@H](O)[C@H](O)CS VHJLVAABSRFDPM-QWWZWVQMSA-N 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 150000004820 halides Chemical class 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- 238000002354 inductively-coupled plasma atomic emission spectroscopy Methods 0.000 description 1
- 229910052809 inorganic oxide Inorganic materials 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 238000001465 metallisation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 1
- 230000020477 pH reduction Effects 0.000 description 1
- 239000002574 poison Substances 0.000 description 1
- 231100000614 poison Toxicity 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- VXNYVYJABGOSBX-UHFFFAOYSA-N rhodium(3+);trinitrate Chemical compound [Rh+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VXNYVYJABGOSBX-UHFFFAOYSA-N 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- HXJUTPCZVOIRIF-UHFFFAOYSA-N sulfolane Chemical compound O=S1(=O)CCCC1 HXJUTPCZVOIRIF-UHFFFAOYSA-N 0.000 description 1
- 125000000542 sulfonic acid group Chemical group 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000001238 wet grinding Methods 0.000 description 1
- 239000010457 zeolite Substances 0.000 description 1
- 229910001928 zirconium oxide Inorganic materials 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
- F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
-
- B01J35/56—
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
- B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
- B01D53/9404—Removing only nitrogen compounds
- B01D53/9409—Nitrogen oxides
- B01D53/9413—Processes characterised by a specific catalyst
- B01D53/9422—Processes characterised by a specific catalyst for removing nitrogen oxides by NOx storage or reduction by cyclic switching between lean and rich exhaust gases (LNT, NSC, NSR)
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
- B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
- B01D53/944—Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
- B01J23/46—Ruthenium, rhodium, osmium or iridium
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/56—Platinum group metals
- B01J23/58—Platinum group metals with alkali- or alkaline earth metals
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- B01J27/02—Sulfur, selenium or tellurium; Compounds thereof
- B01J27/053—Sulfates
-
- B01J35/40—
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/02—Impregnation, coating or precipitation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/02—Impregnation, coating or precipitation
- B01J37/0215—Coating
- B01J37/0221—Coating of particles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/08—Heat treatment
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
- F01N3/28—Construction of catalytic reactors
- F01N3/2803—Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support
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- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
- F01N3/28—Construction of catalytic reactors
- F01N3/2803—Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support
- F01N3/2825—Ceramics
- F01N3/2828—Ceramic multi-channel monoliths, e.g. honeycombs
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- F01N2250/00—Combinations of different methods of purification
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- F01N2370/00—Selection of materials for exhaust purification
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- F01N2510/00—Surface coverings
- F01N2510/06—Surface coverings for exhaust purification, e.g. catalytic reaction
- F01N2510/068—Surface coverings for exhaust purification, e.g. catalytic reaction characterised by the distribution of the catalytic coatings
- F01N2510/0684—Surface coverings for exhaust purification, e.g. catalytic reaction characterised by the distribution of the catalytic coatings having more than one coating layer, e.g. multi-layered coatings
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- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/101—Three-way catalysts
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Abstract
Description
本発明は、内燃機関の排気系に設けられる排ガス浄化用触媒に関する。詳しくは、触媒金属として白金（Ｐｔ）を含み、さらに助触媒成分としてバリウム（Ｂａ）、ストロンチウム（Ｓｒ）等のアルカリ土類金属を含む排ガス浄化用触媒に関する。 The present invention relates to an exhaust gas purifying catalyst provided in an exhaust system of an internal combustion engine. More specifically, the present invention relates to an exhaust gas purifying catalyst containing platinum (Pt) as a catalyst metal and further containing an alkaline earth metal such as barium (Ba) and strontium (Sr) as a promoter component.
自動車エンジン等の内燃機関から排出される排ガスから炭化水素（ＨＣ）、一酸化炭素（ＣＯ）、窒素酸化物（ＮＯｘ）等の有害成分を酸化または還元反応によって除去するための排ガス浄化用触媒として、いわゆる三元触媒が用いられている。三元触媒としては、例えばアルミナ（Ａｌ２Ｏ３）、ジルコニア（ＺｒＯ２）等の無機酸化物からなる多孔質担体に、酸化触媒及び／又は還元触媒として機能する金属（典型的にはＰｔ等の貴金属）を担持させたものが利用されている。
さらに、この種の排ガス浄化触媒には、排ガス浄化機能を向上させ得る助触媒成分が用いられている。例えば、以下の特許文献１，２には、触媒金属としてＰｔを、助触媒としてバリウム（Ｂａ）、ストロンチウム（Ｓｒ）等のアルカリ土類金属を含む従来の排ガス浄化用触媒が記載されている。
Exhaust gas purifying catalyst for removing harmful components such as hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NO x ) from an exhaust gas discharged from an internal combustion engine such as an automobile engine by an oxidation or reduction reaction. A so-called three-way catalyst is used. As the three-way catalyst, for example, a metal (typically Pt or the like) which functions as an oxidation catalyst and / or a reduction catalyst is added to a porous support made of an inorganic oxide such as alumina (Al 2 O 3 ) and zirconia (ZrO 2 ). Noble metal) is used.
Further, a co-catalyst component capable of improving an exhaust gas purifying function is used in this type of exhaust gas purifying catalyst. For example, the following Patent Documents 1 and 2 disclose a conventional exhaust gas purification catalyst containing Pt as a catalyst metal and an alkaline earth metal such as barium (Ba) or strontium (Sr) as a promoter.
ところで、上述したようなアルカリ土類金属の助触媒としての効果を発揮するには、排ガス浄化用触媒の触媒層中においてアルカリ土類金属がＰｔの近傍に存在していることが必要である。そしてまた、排ガス浄化用触媒の全体において助触媒としての効果を発揮するには、Ｐｔとともにアルカリ土類触媒が高度に分散した状態で存在することが重要である。
しかしながら、従来の触媒層の形成技法によると、触媒層（アルカリ土類金属担持領域）中にアルカリ土類金属の偏在が生じており、高度な分散状態で多孔質担体の外表面および細孔内にアルカリ土類金属を担持させることができなかった。このことを換言すれば、触媒層（アルカリ土類金属担持領域）中において多孔質担体の外表面および細孔内に高度に分散した状態で担持されたＰｔの近傍に、アルカリ土類金属を同様に高分散状態で担持（固定）することができなかった。例えば、多孔質担体の外表面に大半のアルカリ土類金属が偏在するなどの不都合があった。
そこで本発明は、かかる従来の課題を解決するべく創出されたものであり、助触媒成分たるアルカリ土類金属を高度な分散状態で多孔質担体に担持させた排ガス浄化用触媒の提供と、そのような高分散な担持を実現し得る製法を提供することを目的とする。
By the way, in order to exhibit the effect of the alkaline earth metal as a cocatalyst as described above, it is necessary that the alkaline earth metal is present near Pt in the catalyst layer of the exhaust gas purifying catalyst. Further, in order to exhibit the effect as a promoter in the entire exhaust gas purifying catalyst, it is important that the alkaline earth catalyst is present in a highly dispersed state together with Pt.
However, according to the conventional catalyst layer forming technique, the alkaline earth metal is unevenly distributed in the catalyst layer (the alkaline earth metal supporting region), and the outer surface and the pores of the porous carrier are highly dispersed in a highly dispersed state. Could not support the alkaline earth metal. In other words, in the catalyst layer (alkaline earth metal supporting region), the alkaline earth metal is similarly placed near the Pt supported in a highly dispersed state on the outer surface and the pores of the porous carrier. Could not be supported (fixed) in a highly dispersed state. For example, there is a disadvantage that most of the alkaline earth metals are unevenly distributed on the outer surface of the porous carrier.
Accordingly, the present invention has been created in order to solve such a conventional problem, and provides an exhaust gas purification catalyst in which an alkaline earth metal as a promoter component is supported on a porous carrier in a highly dispersed state. It is an object of the present invention to provide a production method capable of realizing such highly dispersed support.
本発明者は、助触媒たるＢａ等のアルカリ土類金属の触媒層中における存在形態について詳細に検討した。そして、Ｂａ等のアルカリ土類金属を原料段階から水に不溶性の硫酸塩として使用すると、触媒層においてアルカリ土類金属の偏在を招き、高度な分散状態を実現できないことが確認された。また、Ｂａの硝酸塩のような水溶性化合物を含む原料スラリーを使用し、硫酸や硫酸アンモニウム溶液を当該スラリーに供給してＢａ等のアルカリ土類金属の硫酸塩（不溶体）を生成する場合には、その後の乾燥および焼成段階において当該原料スラリーのｐＨが変化して酸性に偏りすぎ、結果、高分散状態を維持できずにアルカリ土類金属の偏在が生じ、やはり高度な分散状態は実現できなかった。
そこで、本発明者は、Ｂａ等のアルカリ土類金属の原料段階から検討し、アルカリ土類金属の水溶性化合物を、ある種のＳ含有水溶性有機化合物と共存させた原料を用いることにより、触媒層（アルカリ土類金属担持領域）中においてＰｔとともに高度な分散状態でＢａ等のアルカリ土類金属硫酸塩を多孔質担体に配置（担持）することができることを見出し、本発明を完成するに至った。
The present inventor has studied in detail the existence form of an alkaline earth metal such as Ba as a promoter in a catalyst layer. Then, it was confirmed that when an alkaline earth metal such as Ba was used as a sulfate insoluble in water from the raw material stage, the alkaline earth metal was unevenly distributed in the catalyst layer, and a high dispersion state could not be realized. When a raw slurry containing a water-soluble compound such as a nitrate of Ba is used, and a sulfuric acid or ammonium sulfate solution is supplied to the slurry to produce a sulfate (insoluble) of an alkaline earth metal such as Ba. In the subsequent drying and baking stages, the pH of the raw material slurry changes and is excessively biased toward the acidity. As a result, a highly dispersed state cannot be maintained, and the alkaline earth metal is unevenly distributed. Was.
Therefore, the present inventors studied from the raw material stage of alkaline earth metal such as Ba, by using a raw material in which a water-soluble compound of alkaline earth metal coexists with a certain S-containing water-soluble organic compound, It has been found that an alkaline earth metal sulfate such as Ba can be disposed (supported) on a porous carrier in a highly dispersed state together with Pt in a catalyst layer (alkaline earth metal supporting region). Reached.
本発明によって、内燃機関の排気管に配置されて当該内燃機関から排出される排ガスの浄化を行う排ガス浄化用触媒が提供される。
即ち、ここで開示される排ガス浄化用触媒は、基材と、当該基材上に形成された触媒層とを備えている。かかる触媒層は、
無機化合物から構成される多孔質担体と、
当該多孔質担体上に担持されたＰｔと、
当該多孔質担体上に担持された、少なくとも一種のアルカリ土類金属の硫酸塩と、
を備えるアルカリ土類金属担持領域を有している。
そして、ここで開示される排ガス浄化用触媒は、上記触媒層のアルカリ土類金属担持領域の断面について、
ピクセル（区画）サイズ ０．３４μｍ×０．３４μｍ；
測定ピクセル（区画）数 ２５６×２５６：
の条件でＦＥ−ＥＰＭＡによる面分析を行い、前記アルカリ土類金属の元素（Ａｅ）の特性Ｘ線の強度（α：ｃｐｓ）およびＰｔの特性Ｘ線の強度（β：ｃｐｓ）を各ピクセルについて測定し、得られた各ピクセルにおけるαおよびβを用いて算出したピアソンの相関係数をＲＡｅ／Ｐｔとしたとき、
当該ＲＡｅ／Ｐｔの値が０．５以上であることを特徴とする。
According to the present invention, there is provided an exhaust gas purifying catalyst which is disposed in an exhaust pipe of an internal combustion engine and purifies exhaust gas discharged from the internal combustion engine.
That is, the exhaust gas purifying catalyst disclosed herein includes a base material and a catalyst layer formed on the base material. Such a catalyst layer,
A porous carrier composed of an inorganic compound,
Pt supported on the porous carrier;
Supported on the porous carrier, at least one sulfate of an alkaline earth metal,
And an alkaline earth metal supporting region comprising:
And the exhaust gas purifying catalyst disclosed herein is a cross section of the alkaline earth metal supporting region of the catalyst layer,
Pixel (section) size 0.34 μm × 0.34 μm;
Number of measurement pixels (sections) 256 x 256:
The surface analysis by FE-EPMA is performed under the following conditions, and the characteristic X-ray intensity (α: cps) of the alkaline earth metal element (Ae) and the characteristic X-ray intensity (β: cps) of Pt are determined for each pixel. When the Pearson's correlation coefficient calculated using the measured and obtained α and β in each pixel is defined as RAe / Pt ,
The value of RAe / Pt is 0.5 or more.
ここで開示される排ガス浄化用触媒は、本発明によって提供される排ガス浄化用触媒製造方法（詳細は後述する。）により製造され得る触媒製品であり、上述のとおり、ＦＥ−ＥＰＭＡによる面分析の結果に基づいて算出されたピアソンの相関係数（積率相関係数）であるＲＡｅ／Ｐｔが０．５以上であることを特徴とする。
かかる相関係数ＲＡｅ／Ｐｔは、第１変数をＦＥ−ＥＰＭＡによる面分析におけるアルカリ土類金属元素（Ａｅ）の特性Ｘ線強度（α）とし、第２変数を同じ面分析における多Ｐｔの特性Ｘ線強度（β）としたとき、
ＲＡｅ／Ｐｔ＝（共分散）／（αの標準偏差×βの標準偏差）
で求められる相関係数である。
The exhaust gas purifying catalyst disclosed herein is a catalyst product that can be produced by the exhaust gas purifying catalyst production method provided by the present invention (details will be described later), and as described above, is obtained by surface analysis using FE-EPMA. R Ae / Pt, which is a Pearson's correlation coefficient (product moment correlation coefficient) calculated based on the result, is 0.5 or more.
The correlation coefficient R Ae / Pt is obtained by setting the first variable to the characteristic X-ray intensity (α) of the alkaline earth metal element (Ae) in the plane analysis by FE-EPMA, and the second variable to the multi-Pt of the same plane analysis. When the characteristic X-ray intensity (β) is used,
R Ae / Pt = (covariance) / (standard deviation of α × standard deviation of β)
Is the correlation coefficient obtained by
本構成の排ガス浄化用触媒では、触媒層のアルカリ土類金属担持領域において、Ｐｔとアルカリ土類金属元素存在位置（分布）との間に高い相関があること、換言すれば、多孔質担体粒子の全体（即ち担体粒子の外表面および内部（細孔内）の両方）にわたって高度に分散した状態でアルカリ土類金属（硫酸塩）が存在していることを特徴とする。これにより、触媒層のアルカリ土類金属担持領域においてＰｔ粒子の近傍に高頻度でアルカリ土類金属が存在し得るため、当該アルカリ土類金属の助触媒成分としての作用効果を高レベルに発揮させることができる。特に、アルカリ土類金属がＰｔと近接しているため、アルカリ土類金属からの電子供与によるＰｔのＨＣ被毒抑制が起こり、Ｒｉｃｈ雰囲気時のＨＣ浄化性能が向上する。 In the exhaust gas purifying catalyst of this configuration, in the alkaline earth metal supporting region of the catalyst layer, there is a high correlation between Pt and the location (distribution) of the alkaline earth metal element, in other words, the porous carrier particles. Is characterized in that the alkaline earth metal (sulfate) is present in a state of being highly dispersed throughout the whole (ie, both on the outer surface and inside (in pores) of the carrier particles). Thereby, since the alkaline earth metal can be frequently present in the vicinity of the Pt particles in the alkaline earth metal supporting region of the catalyst layer, the effect of the alkaline earth metal as a promoter component is exerted at a high level. be able to. In particular, since the alkaline earth metal is close to Pt, HC poisoning of Pt is suppressed by electron donation from the alkaline earth metal, and the HC purification performance in a Rich atmosphere is improved.
ここで開示される排ガス浄化用触媒の好適な他の一態様では、上記算出したピアソンの相関係数ＲＡｅ／Ｐｔの値が０．７以上であることを特徴とする。
ＲＡｅ／Ｐｔの値が０．７以上で示されるように、本構成の排ガス浄化用触媒は、アルカリ土類金属成分の分散性が高い。このため、助触媒成分としての性能（機能）を触媒層（アルカリ土類金属担持領域）中において高レベルに発揮させることができる。
In another preferred embodiment of the exhaust gas purifying catalyst disclosed herein, the calculated value of the Pearson correlation coefficient RAe / Pt is 0.7 or more.
As shown in the value of RAe / Pt of 0.7 or more, the exhaust gas purifying catalyst of this configuration has a high dispersibility of the alkaline earth metal component. For this reason, the performance (function) as a promoter component can be exhibited at a high level in the catalyst layer (alkaline earth metal supporting region).
多孔質担体に担持されたアルカリ土類金属硫酸塩のＸ線回折法に基づく平均粒径が３０ｎｍ以下であることが特に好ましい。かかる微細な平均粒径のアルカリ土類金属成分は、助触媒成分として特に高い性能を発揮し得る。 It is particularly preferred that the alkaline earth metal sulfate supported on the porous carrier has an average particle size of 30 nm or less based on X-ray diffraction. Such an alkaline earth metal component having a fine average particle size can exhibit particularly high performance as a promoter component.
また、ここで開示される排ガス浄化用触媒の好適な一態様では、上記の触媒層の排ガスが流れる方向の下流側に、Ｒｈを触媒金属とする触媒層をさらに有する。
このとき、Ｒｈを触媒金属とする触媒層への流入ＨＣ量が減少することになるため、ＲｈのＨＣ被毒を抑制することができる。また、アルカリ土類金属が硫酸塩であり、固定されているため、ＲｈとＢａ等のアルカリ土類金属（特にＢａ）とが接触することを防ぎ、ＢａによるＲｈのメタル化抑制を防止することができる。このため、排ガス浄化用触媒のＲｉｃｈ雰囲気時の共存ＮＯｘの浄化作用を向上させることができる。
In one preferred embodiment of the exhaust gas purifying catalyst disclosed herein, the catalyst layer further includes a catalyst layer containing Rh as a catalyst metal on the downstream side in the exhaust gas flowing direction.
At this time, since the amount of HC flowing into the catalyst layer using Rh as the catalyst metal decreases, HC poisoning of Rh can be suppressed. Further, since the alkaline earth metal is a sulfate and fixed, it is possible to prevent Rh from contacting with an alkaline earth metal such as Ba (especially Ba), and to prevent the Ba from being metallized by Ba. Can be. Therefore, it is possible to improve the purification effect of the coexistence NO x when Rich atmosphere of the exhaust gas-purifying catalyst.
また、ここで開示される排ガス浄化用触媒の好適な一態様では、上記アルカリ土類金属硫酸塩として少なくとも硫酸バリウム（ＢａＳＯ４）を有していることを特徴とする。
かかる構成の排ガス浄化用触媒によると、高度に分散したバリウム成分（硫酸バリウム）によって、ＮＯｘを安定的に一時的に吸蔵することができるとともに、当該成分に一時的に吸蔵されたＮＯｘ成分をＰｔにより効果的に還元浄化処理することができる。また、バリウム成分が高度に分散して担体に担持されることにより、ＮＯｘ還元作用を向上させることができる。したがって、本構成の排ガス浄化用触媒は、高性能なＮＯｘ浄化触媒として好適に採用することができる。
In a preferred embodiment of the exhaust gas purifying catalyst disclosed herein, at least barium sulfate (BaSO 4 ) is included as the alkaline earth metal sulfate.
According to the exhaust gas purifying catalyst of this configuration, the highly dispersed barium component (barium sulfate), together with the NO x can be stably temporarily storing temporarily occluded NO x component in the component Can be effectively reduced and purified by Pt. Further, since the barium component is supported in a highly dispersed carrier, it can improve the the NO x reduction effect. Thus, the exhaust gas purifying catalyst of the present configuration can be suitably employed as a high-performance the NO x purification catalyst.
また、本発明は、上記目的を実現するべく、ここで開示される排ガス浄化用触媒を好適に製造し得る方法を提供する。即ち、ここで開示される製造方法は、
内燃機関の排気管に配置されて当該内燃機関から排出される排ガスの浄化を行う排ガス浄化用触媒を製造する方法であって、
基材上に、
無機化合物から構成される多孔質担体と、
当該多孔質担体に担持されたＰｔと、
当該多孔質担体に担持された少なくとも一種のアルカリ土類金属の硫酸塩と、
を備えるアルカリ土類金属担持領域を少なくとも一部に有する触媒層を形成する工程、および
上記触媒層が形成された基材を焼成する工程、
を包含する方法である。
そして、ここで開示される製造方法では、上記触媒層の形成工程において、
（１）以下の成分：
上記多孔質担体を構成する無機化合物粒子；
Ｐｔ粒子、または、Ｐｔを析出させるための前駆物質；
上記アルカリ土類金属の水溶性化合物；および
構成元素としてＳを含有し、上記アルカリ土類金属の硫酸塩を生成可能なＳ含有水溶性有機化合物；
を水系溶媒と混合し、原料懸濁物を調製すること、
（２）上記原料懸濁物を乾燥し、さらに焼成することによって、上記多孔質担体とＰｔとアルカリ土類金属の硫酸塩とが混在する粉末材料を調製すること、
（３）少なくとも上記粉末材料と水系溶媒を含むアルカリ土類金属担持領域形成用スラリーを調製すること、および
（４）上記スラリーを用いて上記基材上に上記アルカリ土類金属担持領域を形成すること、
を包含する。
Further, the present invention provides a method capable of suitably producing the exhaust gas purifying catalyst disclosed herein to achieve the above object. That is, the manufacturing method disclosed here is:
A method for producing an exhaust gas purifying catalyst that is disposed in an exhaust pipe of an internal combustion engine and purifies exhaust gas discharged from the internal combustion engine,
On the substrate,
A porous carrier composed of an inorganic compound,
Pt supported on the porous carrier;
A sulfate of at least one alkaline earth metal supported on the porous carrier,
Forming a catalyst layer having at least a portion of an alkaline earth metal-supported region comprising: and firing the substrate on which the catalyst layer is formed,
It is a method including.
Then, in the production method disclosed herein, in the step of forming the catalyst layer,
(1) The following components:
Inorganic compound particles constituting the porous carrier;
Pt particles or precursors for depositing Pt;
A water-soluble compound of the alkaline earth metal; and an S-containing water-soluble organic compound containing S as a constituent element and capable of forming a sulfate of the alkaline earth metal;
Is mixed with an aqueous solvent to prepare a raw material suspension,
(2) preparing a powder material in which the porous carrier, Pt, and a sulfate of an alkaline earth metal are mixed by drying and firing the raw material suspension;
(3) preparing a slurry for forming an alkaline earth metal-supporting region containing at least the powder material and an aqueous solvent; and (4) forming the alkaline-earth metal-supporting region on the substrate using the slurry. thing,
Is included.
かかる構成の排ガス浄化用触媒製造方法では、アルカリ土類金属の水溶性化合物と上記のように規定されるＳ含有水溶性有機化合物とを担体成分（無機化合物粒子）ならびに触媒金属成分（Ｐｔ粒子またはＰｔの前駆体である化合物）とともに混合させた原料（懸濁物）をアルカリ土類金属担持領域形成用途に使用する。
調製した原料懸濁物では、アルカリ土類金属水溶性化合物とＳ含有水溶性有機化合物とがともに水系溶媒に溶解している。このとき、Ｓ含有水溶性有機化合物は、原料懸濁物のｐＨを急激に低下（即ち懸濁液の酸性化）させることが無く、アルカリ土類金属水溶性化合物とＳ含有水溶性有機化合物は、ともに水溶性を保ったまま、担体成分である無機化合物粒子（二次粒子）の内部（細孔内）にまで行き渡ることができる。
そして、調製した原料懸濁物を乾燥させ、焼成する。その課程において、含有成分であるアルカリ土類金属の水溶性化合物と上記Ｓ含有水溶性有機化合物とが反応し、不溶性のアルカリ土類金属硫酸塩が無機化合物粒子の内部および外部において形成され、その存在部位において固定される。
したがって、本構成の製造方法によると、多孔質担体粒子の全体（即ち担体粒子の外表面および内部（細孔内）の両方）にわたって高度に分散した状態でアルカリ土類金属が存在していることを特徴とするアルカリ土類金属担持領域を触媒層の全体又は一部に有する排ガス浄化用触媒を、好適に製造することができる。
In the method for producing an exhaust gas purifying catalyst having such a configuration, the water-soluble compound of an alkaline earth metal and the S-containing water-soluble organic compound defined as described above are mixed with a carrier component (inorganic compound particles) and a catalyst metal component (Pt particles or The raw material (suspension) mixed with the compound which is a precursor of Pt) is used for forming an alkaline earth metal supporting region.
In the prepared raw material suspension, both the alkaline earth metal water-soluble compound and the S-containing water-soluble organic compound are dissolved in the aqueous solvent. At this time, the S-containing water-soluble organic compound does not rapidly lower the pH of the raw material suspension (that is, acidifies the suspension), and the alkaline-earth metal water-soluble compound and the S-containing water-soluble organic compound are In addition, it is possible to reach the inside (in the pores) of the inorganic compound particles (secondary particles) as the carrier component while maintaining the water solubility.
Then, the prepared raw material suspension is dried and fired. In the process, the water-soluble compound of the alkaline earth metal, which is the contained component, reacts with the S-containing water-soluble organic compound, and insoluble alkaline earth metal sulfate is formed inside and outside the inorganic compound particles. Fixed at the site of presence.
Therefore, according to the production method of this configuration, the alkaline earth metal is present in a state of being highly dispersed throughout the entire porous carrier particles (ie, both the outer surface and the inside (in the pores) of the carrier particles). An exhaust gas purifying catalyst having an alkaline earth metal-supporting region in the whole or a part of the catalyst layer, which is characterized by the above, can be preferably produced.
ここで開示される排ガス浄化用触媒製造方法の好適な一態様では、Ｓ含有水溶性有機化合物として、スルホ基（−ＳＯ３Ｈ）、スルホニル基（−Ｓ（＝Ｏ）２−）およびスルフィニル基（−Ｓ（＝Ｏ）−）のうちの少なくとも一つの官能基を有する水溶性有機物が使用されることを特徴とする。
かかるＳを含む官能基を有する有機化合物は、上記原料懸濁物を調製するためのＳ含有水溶性有機化合物として好ましい。
In a preferred embodiment of the method for producing an exhaust gas purifying catalyst disclosed herein, as the S-containing water-soluble organic compound, a sulfo group (—SO 3 H), a sulfonyl group (—S (＝ O) 2 —), and a sulfinyl group A water-soluble organic substance having at least one functional group of (-S (= O)-) is used.
Such an organic compound having an S-containing functional group is preferable as the S-containing water-soluble organic compound for preparing the raw material suspension.
また、ここで開示される排ガス浄化用触媒製造方法の好適な他の一態様では、上記アルカリ土類金属の水溶性化合物として、Ｂａ、ＳｒおよびＣａのうちから選択される何れかのアルカリ土類金属の酢酸塩、亜硝酸塩またはヨウ化物が使用されることを特徴とする。
かかる酢酸塩、亜硝酸塩またはヨウ化物は、良好な水溶性を有し、上記原料懸濁物を調製するためのアルカリ土類金属の水溶性化合物として好ましい。
In another preferred embodiment of the method for producing an exhaust gas purifying catalyst disclosed herein, as the water-soluble compound of an alkaline earth metal, any one of Ba, Sr and Ca is selected from the group consisting of alkaline earth metals. It is characterized in that metal acetates, nitrites or iodides are used.
Such acetate, nitrite or iodide has good water solubility and is preferred as a water-soluble alkaline earth metal compound for preparing the above-mentioned raw material suspension.
以下、図面を適宜参照しつつ本発明の好適ないくつかの実施形態を説明する。なお、本明細書において特に言及している事項以外の事柄であって本発明の実施に必要な事柄は、当該分野における従来技術に基づく当業者の設計事項として把握され得る。本発明は、本明細書に開示されている内容と当該分野における技術知識とに基づいて実施することができる。なお、後述する図１〜図２は、本発明の内容を理解するために模式的に示したものであり、各図における寸法関係（長さ、幅、厚さなど）は、実際の寸法関係を反映するものではない。 Hereinafter, some preferred embodiments of the present invention will be described with reference to the drawings as appropriate. It should be noted that matters other than matters specifically mentioned in the present specification and necessary for carrying out the present invention can be grasped as design matters of those skilled in the art based on conventional techniques in the relevant field. The present invention can be implemented based on the contents disclosed in this specification and technical knowledge in the relevant field. 1 and 2 described later are schematically shown for understanding the contents of the present invention, and the dimensional relationships (length, width, thickness, etc.) in the respective drawings are based on actual dimensional relationships. It does not reflect that.
ここで開示される排ガス浄化用触媒は、上述した性状でアルカリ土類金属の硫酸塩が触媒層の少なくとも一部（即ち、触媒層中における予め設計されたアルカリ土類金属担持領域）において高度に分散した状態で備えられていることで特徴づけられる排ガス浄化用触媒であり、その他の構成は特に限定されない。ここで開示される排ガス浄化用触媒は、後述する担体、基材の種類を適宜選択し、用途に応じて所望する形状に成形することによって種々の内燃機関、特に自動車エンジンの排気系（排気管）に配置することができる。
以下の説明では、主として本発明の排ガス浄化用触媒を自動車のガソリンエンジンの排気管に設けられる三元触媒に適用することを前提として説明しているが、ここで開示される排ガス浄化用触媒をかかる用途に限定することを意図したものではない。
In the exhaust gas purifying catalyst disclosed herein, the sulfate of the alkaline earth metal having the above-mentioned properties has a high degree of activity in at least a part of the catalyst layer (that is, a pre-designed alkaline earth metal supporting region in the catalyst layer). An exhaust gas purifying catalyst characterized by being provided in a dispersed state, and other configurations are not particularly limited. The exhaust gas purifying catalyst disclosed herein can be used in various types of internal combustion engines, in particular, automobile engine exhaust systems (exhaust pipes) by appropriately selecting the types of carriers and base materials described below and molding them into desired shapes according to the applications. ).
The following description has been made mainly on the assumption that the exhaust gas purifying catalyst of the present invention is applied to a three-way catalyst provided in an exhaust pipe of an automobile gasoline engine. It is not intended to be limited to such applications.
＜基材＞
ここで開示される排ガス浄化用触媒の骨格を構成する基材としては、従来この種の用途に用いられる種々の素材及び形態のものを採用することができる。例えば、高耐熱性を有するコージェライト、炭化ケイ素（ＳｉＣ）等のセラミックスが好適である。或いは、合金（ステンレス鋼等）製の基材を使用することができる。形状についても従来の排ガス浄化用触媒と同様でよい。一例として図１に示す排ガス浄化用触媒１０のように、外形が円筒形状であるハニカム基材１であって、その筒軸方向に排ガス流路としての貫通孔（セル）２が設けられ、各セル２を仕切る隔壁（リブ壁）４に排ガスが接触可能となっているものが挙げられる。基材１の形状はハニカム形状の他にフォーム形状、ペレット形状などとすることができる。或いは、排ガスが一方の入り側セルからセル隔壁を通過して他方の出側セルに流れていく所謂ウォールスルー型（ウォールフロー型ともいう。）の基材であってもよい。また、基材全体の外形については、円筒形に代えて楕円筒形、多角筒形を採用してもよい。
<Substrate>
As the base material constituting the skeleton of the exhaust gas purifying catalyst disclosed herein, various materials and forms conventionally used for this type of application can be adopted. For example, ceramics such as cordierite and silicon carbide (SiC) having high heat resistance are suitable. Alternatively, an alloy (such as stainless steel) base material can be used. The shape may be the same as that of a conventional exhaust gas purifying catalyst. As an example, as in an exhaust gas purifying catalyst 10 shown in FIG. 1, a honeycomb substrate 1 having a cylindrical outer shape is provided with through holes (cells) 2 as exhaust gas channels in the cylinder axis direction. One in which exhaust gas can contact a partition wall (rib wall) 4 that partitions the cell 2 can be used. The shape of the substrate 1 can be a foam shape, a pellet shape, or the like in addition to the honeycomb shape. Alternatively, a so-called wall-through type (also referred to as a wall-flow type) base material in which exhaust gas flows from one entry-side cell through a cell partition to the other exit-side cell may be used. Further, the outer shape of the entire base material may be an elliptical cylindrical shape or a polygonal cylindrical shape instead of the cylindrical shape.
＜白金（Ｐｔ）＞
ここで開示される排ガス浄化用触媒の触媒層に備えられる触媒金属として、Ｐｔが用いられる。
Ｐｔは、排ガスとの接触面積を高める観点から十分に小さい粒径の微粒子として使用されることが好ましい。典型的には平均粒径（例えばＴＥＭ観察により求められる粒径の平均値、或いは、Ｘ線回折法に基づく平均値であることが好ましい。）は１ｎｍ以上１５ｎｍ以下程度であり、１０ｎｍ以下、７ｎｍ以下、更には５ｎｍ以下であることが特に好ましい。
かかる触媒金属の担持率（担体を１００質量％としたときのＰｔ含有率）は、特に限定されないが、通常２質量％以下、例えば０．０５質量％以上２質量％以下であることが適当であり、０．２質量％以上１質量％以下程度であることが好ましい。担持率が上記範囲より少なすぎると、Ｐｔによる触媒効果が得られにくい。かかる担持率が上記範囲より多すぎるとコスト面で不利となる。
<Platinum (Pt)>
Pt is used as a catalyst metal provided in the catalyst layer of the exhaust gas purifying catalyst disclosed herein.
Pt is preferably used as fine particles having a sufficiently small particle size from the viewpoint of increasing the contact area with the exhaust gas. Typically, the average particle size (for example, the average value of the particle size obtained by TEM observation, or preferably the average value based on the X-ray diffraction method) is about 1 nm or more and 15 nm or less, and 10 nm or less and 7 nm or less. It is particularly preferable that the thickness be 5 nm or less.
The loading ratio of the catalyst metal (Pt content when the carrier is 100% by mass) is not particularly limited, but is usually 2% by mass or less, for example, 0.05% by mass or more and 2% by mass or less. Yes, it is preferable that it is about 0.2% by mass to 1% by mass. If the loading is less than the above range, it is difficult to obtain the catalytic effect of Pt. If the loading ratio is too large, the cost will be disadvantageous.
＜担体＞
触媒層を構成し、Ｐｔならびにその他の成分（例えばアルカリ土類金属）を担持する多孔質担体としては、従来の排ガス浄化用触媒と同様の無機化合物が使用される。
比表面積（ＢＥＴ法により測定される比表面積。以下同じ。）がある程度大きい多孔質担体が好適に用いられる。好適なものとして、例えば、アルミナ（Ａｌ２Ｏ３）、ジルコニア（ＺｒＯ２）、セリア（ＣｅＯ２）、シリカ（ＳｉＯ２）、チタニア（ＴｉＯ２）、それらの固溶体（例えばセリア−ジルコニア複合酸化物（ＣＺ複合酸化物）、或いはそれらの組み合わせが挙げられる。
<Carrier>
As the porous carrier that forms the catalyst layer and supports Pt and other components (for example, alkaline earth metal), the same inorganic compounds as those used in conventional exhaust gas purifying catalysts are used.
A porous support having a relatively large specific surface area (specific surface area measured by the BET method; the same applies hereinafter) is preferably used. Preferable examples include alumina (Al 2 O 3 ), zirconia (ZrO 2 ), ceria (CeO 2 ), silica (SiO 2 ), titania (TiO 2 ), and solid solutions thereof (eg, ceria-zirconia composite oxide). (CZ composite oxide) or a combination thereof.
排ガス浄化用触媒の熱安定性を高めるという観点からは、耐熱性のよいアルミナ、ジルコニア等の無機化合物を担体若しくは非担持体（即ち、Ｐｔやアルカリ土類金属を担持させていない触媒層の構成成分をいう。以下同じ。）として触媒層に含ませることが好ましい。
担体又は非担持体の粒子（例えばアルミナ粉末やＣＺ複合酸化物粉末）としては、比表面積が５０〜５００ｍ２／ｇ（例えば２００〜４００ｍ２／ｇ）であることが耐熱性、構造安定性の観点から好ましい。また、担体粒子のＴＥＭ観察に基づく平均粒径は、１ｎｍ以上５００ｎｍ以下（より好ましくは５ｎｍ以上３００ｎｍ以下）程度であることが好ましい。
また、このような無機化合物（セラミックス）を担体として使用する場合、好ましくは触媒容積が１Ｌあたりの触媒金属含有量が０．１〜５ｇ／Ｌ程度が適当であり、０．２〜２ｇ／Ｌ程度が好ましい。触媒金属含有量が多すぎるとコスト的に好ましくなく、少なすぎると排ガス浄化能が低いために好ましくない。なお、本明細書において触媒容積が１Ｌというときは、基材の純容積に加えて内部の空隙（セル）容積を含む（即ち当該空隙（セル）内に形成された触媒層を含む）嵩容積が１Ｌであることをいう。
From the viewpoint of improving the thermal stability of the exhaust gas purifying catalyst, a heat-resistant inorganic compound such as alumina or zirconia is used as a carrier or a non-supporting material (that is, the structure of the catalyst layer not supporting Pt or alkaline earth metal). It is preferable to include the catalyst component in the catalyst layer.
The particles of the carrier or the unsupported body (for example, alumina powder or CZ composite oxide powder) should have a specific surface area of 50 to 500 m 2 / g (for example, 200 to 400 m 2 / g) for heat resistance and structural stability. Preferred from a viewpoint. The average particle size of the carrier particles based on TEM observation is preferably about 1 nm or more and 500 nm or less (more preferably 5 nm or more and 300 nm or less).
When such an inorganic compound (ceramic) is used as a carrier, the catalyst metal content is preferably about 0.1 to 5 g / L per 1 L of the catalyst volume, and 0.2 to 2 g / L. The degree is preferred. If the catalyst metal content is too large, it is not preferable in terms of cost, and if it is too small, it is not preferable because the exhaust gas purification ability is low. In the present specification, when the catalyst volume is 1 L, the bulk volume includes the internal void (cell) volume (that is, includes the catalyst layer formed in the void (cell)) in addition to the pure volume of the base material. Is 1L.
＜アルカリ土類金属担持領域＞
基材上に形成される触媒層は、排ガスを浄化する場として、排ガス浄化用触媒の主体をなすものであるが、ここで開示される排ガス浄化用触媒においては、上記のとおり、触媒層の少なくとも一部（又は全部）が、アルカリ土類金属担持領域を構成する。
本明細書において「アルカリ土類金属担持領域」は、多孔質担体とＰｔとアルカリ土類金属硫酸塩（硫酸バリウム、硫酸ストロンチウム等）とを備える触媒層の一部又は全部をいう。ここで「触媒層の一部」とは、排ガス浄化用触媒として機能し得る一区画をいうのであって、例えば担体粒子数個〜数十個のような機能的に一区画と呼べないような微視的な一部を意味しない用語である。
<Alkaline earth metal loading area>
The catalyst layer formed on the base material, as a place for purifying the exhaust gas, is the main component of the exhaust gas purification catalyst, but in the exhaust gas purification catalyst disclosed herein, as described above, At least a part (or all) constitutes an alkaline earth metal supporting region.
In the present specification, the “alkaline earth metal supporting region” refers to a part or the whole of a catalyst layer including a porous carrier, Pt, and an alkaline earth metal sulfate (such as barium sulfate and strontium sulfate). Here, "part of the catalyst layer" refers to one section that can function as an exhaust gas purifying catalyst, such as a functionally one section such as several to several tens of carrier particles. This is a term that does not mean a microscopic part.
触媒層に担持されるＰｔの配置（分布）、等についてもアルカリ土類金属担持領域の決定と同様、種々の目的に応じて適宜設定することができる。例えば、図２に示す積層構造の触媒層６において、従来品と同様、上層６Ａと下層６Ｂとで担体の種類や当該担体に担持される触媒金属の種類や含有割合を異ならせることができる。
具体的に例えば、一例として図２に示す触媒層６のように、基材１上に形成された相互に内容の異なる上下二層を有する積層構造タイプの触媒層６の場合、基材１に近接する下層６Ｂと触媒層６の表層部分を構成する上層６Ａのうちのいずれか一層若しくは両方をアルカリ土類金属担持領域として形成することができる。或いは、図示されるような積層構造若しくは単層構造の触媒層において、その排ガスが流れる方向に沿って、上流側（又は下流側）の一部（例えば全体の１０ｖｏｌ％以上）をアルカリ土類金属担持領域としてもよい。
ここで、アルカリ土類金属担持領域を有する触媒層の排ガスが流れる方の下流側に、Ｒｈを触媒金属とする触媒層をさらに有する構成とすることが好ましい。このとき、Ｒｈを触媒金属とする触媒層への流入ＨＣ量が減少することになるため、ＲｈのＨＣ被毒を抑制することができる。また、アルカリ土類金属が硫酸塩であり、固定されているため、ＲｈとＢａ等のアルカリ土類金属（特にＢａ）とが接触することを防ぎ、ＢａによるＲｈのメタル化抑制を防止することができる。このため、排ガス浄化用触媒のＲｉｃｈ雰囲気時の共存ＮＯｘの浄化作用を向上させることができる。
The arrangement (distribution) and the like of Pt carried on the catalyst layer can be appropriately set according to various purposes, similarly to the determination of the alkaline earth metal carrying region. For example, in the catalyst layer 6 having a laminated structure shown in FIG. 2, the type of the carrier and the type and content ratio of the catalyst metal carried on the carrier can be different between the upper layer 6A and the lower layer 6B as in the conventional product.
More specifically, for example, as in the case of a catalyst layer 6 shown in FIG. 2, in the case of a catalyst layer 6 of a laminated structure having two upper and lower layers having different contents formed on the base material 1, Either one or both of the adjacent lower layer 6B and the upper layer 6A constituting the surface layer portion of the catalyst layer 6 can be formed as an alkaline earth metal supporting region. Alternatively, in a catalyst layer having a laminated structure or a single-layer structure as shown in the figure, a part of the upstream (or downstream) (for example, 10 vol% or more of the whole) is alkaline earth metal along the direction in which the exhaust gas flows. It may be a carrying area.
Here, it is preferable that a catalyst layer having Rh as a catalyst metal is further provided on the downstream side of the catalyst layer having the alkaline earth metal supporting region where exhaust gas flows. At this time, since the amount of HC flowing into the catalyst layer using Rh as the catalyst metal decreases, HC poisoning of Rh can be suppressed. Further, since the alkaline earth metal is a sulfate and fixed, it is possible to prevent Rh from contacting with an alkaline earth metal such as Ba (especially Ba), and to prevent the Ba from being metallized by Ba. Can be. Therefore, it is possible to improve the purification effect of the coexistence NO x when Rich atmosphere of the exhaust gas-purifying catalyst.
このような構成の例としては、上層６Ａをアルカリ土類金属担持領域とし、Ｒｈを、アルカリ土類金属担持領域ではない下層６Ｂ側に含ませる構成、単層構造または積層構造の触媒層において、排ガスが流れる方向の上流側の一部（例えば全体の１０ｖｏｌ％以上）をアルカリ土類金属担持領域とし、残りの下流側の領域にＲｈを含有させる構成、上流側がアルカリ土類金属担持領域を含有する単層構造であり、下流側がＲｈを含有する上層とアルカリ土類金属担持領域を含有する下層の積層構造である構成等が挙げられる。 As an example of such a configuration, in a configuration in which the upper layer 6A is an alkaline-earth metal supporting region and Rh is included in the lower layer 6B which is not the alkaline-earth metal supporting region, in a catalyst layer having a single-layer structure or a laminated structure, A configuration in which part of the upstream side in the direction in which the exhaust gas flows (for example, 10 vol% or more of the whole) is an alkaline earth metal supporting region, and Rh is contained in the remaining downstream region, and the upstream side contains the alkaline earth metal supporting region. And the like, wherein the downstream side has a laminated structure of an upper layer containing Rh and a lower layer containing an alkaline earth metal supporting region.
なお、アルカリ土類金属担持領域に含ませる好適な硫酸塩を構成するアルカリ土類金属元素としては、バリウム（Ｂａ）、ストロンチウム（Ｓｒ）、カルシウム（Ｃａ）が挙げられる。助触媒成分として高い機能を発揮させ得る観点から、ＢａおよびＳｒが好適であり、Ｂａが特に好ましい。硫酸バリウム（ＢａＳＯ４）は、融点が極めて高く安定であり、さらには水への溶解度は極めて低いため、担体に担持させるアルカリ土類金属として好適である。 In addition, barium (Ba), strontium (Sr), and calcium (Ca) are mentioned as an alkaline earth metal element which constitutes a suitable sulfate contained in the alkaline earth metal supporting region. Ba and Sr are preferable, and Ba is particularly preferable, from the viewpoint of exhibiting a high function as a promoter component. Barium sulfate (BaSO 4 ) has a very high melting point and is stable, and further has a very low solubility in water, and thus is suitable as an alkaline earth metal to be supported on a carrier.
触媒層には、Ｐｔ、アルカリ土類金属の他に、種々の補助的成分を配置することができる。典型例として、酸素吸蔵放出成分（Ｏｘｙｇｅｎ Ｓｔｏｒａｇｅ Ｃｏｍｐｏｎｅｎｔ：ＯＳＣ）が挙げられる。ＯＳＣ材として、酸化ジルコニウム（ジルコニア）、酸化セリウム（セリア）、ゼオライト等の使用が好適である。また、高い耐熱性および吸蔵・放出速度の観点から、上記のセリア−ジルコニア複合酸化物（ＣＺ複合酸化物）をＯＳＣ材として利用することが好ましい。 In the catalyst layer, various auxiliary components can be arranged in addition to Pt and the alkaline earth metal. A typical example is an oxygen storage / storage component (OSC). As the OSC material, use of zirconium oxide (zirconia), cerium oxide (ceria), zeolite, or the like is preferable. Further, from the viewpoint of high heat resistance and occlusion / release speed, it is preferable to use the above-mentioned ceria-zirconia composite oxide (CZ composite oxide) as an OSC material.
多孔質担体に担持されたアルカリ土類金属硫酸塩のＸ線回折法に基づく平均粒径が３０ｎｍ以下であることが特に好ましい。かかる微細な平均粒径のアルカリ土類金属成分は、助触媒成分として特に高い性能を発揮し得る。 It is particularly preferred that the alkaline earth metal sulfate supported on the porous carrier has an average particle size of 30 nm or less based on X-ray diffraction. Such an alkaline earth metal component having a fine average particle size can exhibit particularly high performance as a promoter component.
＜ピアソンの相関係数＞
ここで開示される排ガス浄化用触媒のアルカリ土類金属担持領域におけるアルカリ土類金属の分散性に関し、触媒層６のアルカリ土類金属担持領域の断面について、
ピクセルサイズ ０．３４μｍ×０．３４μｍ；
測定ピクセル数 ２５６×２５６；
の条件でＦＥ−ＥＰＭＡによる面分析を行い、前記アルカリ土類金属の元素（Ａｅ）の特性Ｘ線の強度（α：ｃｐｓ）およびＰｔの特性Ｘ線の強度（β：ｃｐｓ）を各ピクセルについて測定し、得られた各ピクセルにおけるαおよびβを用いて算出したピアソンの相関係数をＲＡｅ／Ｐｔとしたとき、ＲＡｅ／Ｐｔの値が０．５以上である。
<Pearson's correlation coefficient>
Regarding the dispersibility of the alkaline earth metal in the alkaline earth metal supporting region of the exhaust gas purifying catalyst disclosed herein, regarding the cross section of the alkaline earth metal supporting region of the catalyst layer 6,
Pixel size 0.34 μm × 0.34 μm;
Number of measured pixels 256 × 256;
The surface analysis by FE-EPMA is performed under the following conditions, and the characteristic X-ray intensity (α: cps) of the alkaline earth metal element (Ae) and the characteristic X-ray intensity (β: cps) of Pt are determined for each pixel. measured, when Pearson's correlation coefficient was calculated using the α and β in the obtained each pixel was R Ae / Pt, the value of R Ae / Pt is 0.5 or more.
アルカリ土類金属が担体内部（特に担体二次粒子内部）に高度に分散して担持されると、Ｐｔの存在位置とアルカリ土類金属の存在位置との間に相関関係が認められるほどに、Ｐｔとアルカリ土類金属が近接化する。
アルカリ土類金属が担体内部（特に担体二次粒子内部）に高度に分散し、Ｐｔとアルカリ土類金属が近接化した状態は、ＲＡｅ／Ｐｔの値が０．５以上であることにより得ることができる。
ＲＡｅ／Ｐｔの値が０．５以上である場合、アルカリ土類金属の助触媒成分としての作用効果を高レベルに発揮させることができる。特に、アルカリ土類金属がＰｔと近接しているため、アルカリ土類金属からの電子供与によるＰｔのＨＣ被毒抑制が起こり、Ｒｉｃｈ雰囲気時のＨＣ浄化性能が向上する。
When the alkaline earth metal is highly dispersed and supported inside the carrier (particularly, inside the secondary particles of the carrier), the correlation between the location of Pt and the location of the alkaline earth metal is so high that the correlation is recognized. Pt and the alkaline earth metal become closer.
A state in which the alkaline earth metal is highly dispersed inside the carrier (particularly inside the secondary particles of the carrier) and Pt and the alkaline earth metal are brought close to each other is obtained by the value of RAe / Pt being 0.5 or more. be able to.
When the value of RAe / Pt is 0.5 or more, the effect of the alkaline earth metal as a promoter component can be exhibited at a high level. In particular, since the alkaline earth metal is close to Pt, HC poisoning of Pt is suppressed by electron donation from the alkaline earth metal, and the HC purification performance in a Rich atmosphere is improved.
ＲＡｅ／Ｐｔの値は、高い方が、本構成の排ガス浄化用触媒におけるアルカリ土類金属成分の分散性が高い。したがって、助触媒成分としての性能（機能）を触媒層（アルカリ土類金属担持領域）中において高レベルに発揮させることができる。よって、ＲＡｅ／Ｐｔの値は、０．６以上が好ましく、０．７以上がより好ましい。 The higher the value of RAe / Pt , the higher the dispersibility of the alkaline earth metal component in the exhaust gas purifying catalyst of the present configuration. Therefore, the performance (function) as a promoter component can be exhibited at a high level in the catalyst layer (the alkaline earth metal-supporting region). Therefore, the value of RAe / Pt is preferably 0.6 or more, and more preferably 0.7 or more.
ピアソンの相関係数：ＲＡｅ／ｐｔは、ＦＥ−ＥＰＭＡによる面分析を行い、アルカリ土類金属の元素（Ａｅ）の特性Ｘ線の強度（α：ｃｐｓ）およびＰｔの特性Ｘ線の強度（β：ｃｐｓ）を各ピクセルについて測定し、得られた各ピクセルにおけるαおよびβを用いて算出することができる。
ＦＥ（Field Emission）−ＥＰＭＡ（Electron Probe Micro Analysis）は、電界放出型電子線マイクロアナライザとも呼ばれる分析法であり、高い精度で試料の所定の領域における元素分析とマッピングを行うことができる。かかるＦＥ−ＥＰＭＡを採用して、排ガス浄化用触媒の触媒層（アルカリ土類金属担持領域）における上記αとβを所定のピクセル数で測定し、得られたデータを用いた計算によってＲＡｅ／Ｐｔを求めることができる。
即ち、ピアソンの相関係数（積率相関係数）であるＲＡｅ／Ｐｔは、
ＲＡｅ／Ｐｔ＝（共分散）／（αの標準偏差×βの標準偏差）であり、具体的には、以下の式（１）によって求めることができる。
Pearson's correlation coefficient: R Ae / pt was obtained by performing a surface analysis by FE-EPMA, and determining the characteristic X-ray intensity (α: cps) of the alkaline earth metal element (Ae) and the characteristic X-ray intensity of Pt (α). β: cps) can be measured for each pixel, and can be calculated using α and β at each obtained pixel.
FE (Field Emission) -EPMA (Electron Probe Micro Analysis) is an analysis method also called a field emission electron beam microanalyzer, and can perform element analysis and mapping in a predetermined region of a sample with high accuracy. By adopting such FE-EPMA, the above α and β in the catalyst layer (alkaline earth metal supporting region) of the exhaust gas purifying catalyst are measured with a predetermined number of pixels, and R Ae / Pt can be determined.
That is, R Ae / Pt which is the Pearson's correlation coefficient (product moment correlation coefficient) is
R Ae / Pt = (covariance) / (standard deviation of α × standard deviation of β), which can be specifically determined by the following equation (1).
かかる式（１）に基づく相関係数ＲＡｅ／Ｐｔの算出は、市販される一般的な表計算ソフトを用いることにより、特に難しい計算処理を手計算で行うことなく導き出すことができる。例えば、マイクロソフト社製品であるエクセル（商標）のCORREL 関数機能を利用することによって簡単に導き出すことができる。 The calculation of the correlation coefficient R Ae / Pt based on the equation (1) can be derived by using commercially available general spreadsheet software without performing particularly difficult calculation processing by hand. For example, it can be easily derived by using the CORREL function function of Excel (trademark) manufactured by Microsoft Corporation.
また、相関係数算出のためのデータ収集に関しては、ＦＥ−ＥＰＭＡによる面分析を市販装置のマニュアルにしたがって操作することによって行うことができる。
概略すれば、先ず、面分析用の排ガス浄化用触媒の触媒層（アルカリ土類金属担持領域）を切り出して用いるか、或いは上記粉末材料の表面を研磨することで断面を出し、導電性物質（典型的には炭素）を蒸着させ、ＥＰＭＡ分析用試料とする。そして、市販の装置（例えば日本電子株式会社製の型式：ＪＸＡ−８５３０Ｆ等の電子線マイクロアナライザ）を使用して、面分析を行う。
ここで、ピクセル（区画）サイズは０．３４μｍ×０．３４μｍとし、測定ピクセル（区画）数は２００×２００以上、例えば２５６×２５６とすることができる。測定条件は、分析装置にもよるので特に限定しないが、典型的ないくつかの測定条件として、
加速電圧：１０ｋＶ〜３０ｋＶ（例えば２０ｋＶ）、
照射電流：５０ｎＡ〜５００ｎＡ（例えば１００ｎＡ）、
最小プローブ径：５００ｎｍ以下（例えば１００ｎｍ）、
単位測定時間：４０ｍｓ〜１００ｍｓ（例えば５０ｍｓ）、
が挙げられる。
また、市販装置に添付のアプリケーション（コンピュータソフトウェア）を用いてＦＥ−ＥＰＭＡによる面分析の結果を元素マッピングとして表示することもできる（後述する図面参照）。
The data collection for calculating the correlation coefficient can be performed by operating the surface analysis by FE-EPMA according to the manual of a commercially available device.
Briefly, first, a catalyst layer (alkaline earth metal supporting region) of an exhaust gas purifying catalyst for surface analysis is cut out and used, or a cross section is formed by polishing the surface of the powder material to obtain a conductive material ( Typically, carbon) is vapor-deposited to obtain a sample for EPMA analysis. Then, surface analysis is performed using a commercially available device (for example, an electron beam microanalyzer such as JXA-8530F manufactured by JEOL Ltd.).
Here, the pixel (section) size can be 0.34 μm × 0.34 μm, and the number of measurement pixels (sections) can be 200 × 200 or more, for example, 256 × 256. The measurement conditions are not particularly limited because they depend on the analyzer, but as typical measurement conditions,
Acceleration voltage: 10 kV to 30 kV (for example, 20 kV),
Irradiation current: 50 nA to 500 nA (for example, 100 nA);
Minimum probe diameter: 500 nm or less (for example, 100 nm),
Unit measurement time: 40 ms to 100 ms (for example, 50 ms),
Is mentioned.
In addition, the results of surface analysis by FE-EPMA can be displayed as element mapping using an application (computer software) attached to a commercially available device (see the drawings described later).
本実施形態に係る排ガス浄化用触媒の製造方法は、基材上に、無機化合物から構成される多孔質担体と、当該多孔質担体に担持されたＰｔと、当該多孔質担体に担持された少なくとも一種のアルカリ土類金属の硫酸塩と、を備えるアルカリ土類金属担持領域を少なくとも一部に有する触媒層を形成する工程、および当該触媒層が形成された基材を焼成する工程、を包含する The method for producing an exhaust gas purifying catalyst according to the present embodiment includes, on a substrate, a porous carrier composed of an inorganic compound, Pt supported on the porous carrier, and at least supported on the porous carrier. A step of forming a catalyst layer having at least a portion of an alkaline earth metal-supporting region comprising one kind of alkaline earth metal sulfate, and a step of firing the substrate on which the catalyst layer is formed.
ここで、当該触媒層の形成工程では、先ず、当該多孔質担体を構成する無機化合物粒子；Ｐｔ粒子またはＰｔを析出させるための前駆物質；当該アルカリ土類金属の水溶性化合物；および構成元素としてＳを含有し、前記アルカリ土類金属の硫酸塩を生成可能なＳ含有水溶性有機化合物；を水系溶媒と混合し、原料懸濁物を調製する。
次いで、原料懸濁物を乾燥し、さらに焼成することによって、前記多孔質担体とＰｔとアルカリ土類金属の硫酸塩とが混在する粉末材料を調製する。
その後、少なくとも前記粉末材料と水系溶媒を含むアルカリ土類金属担持領域形成用スラリーを調製する。
その後、前記スラリーを用いて前記基材上に前記アルカリ土類金属担持領域を形成する。
Here, in the step of forming the catalyst layer, first, inorganic compound particles constituting the porous carrier; Pt particles or a precursor for precipitating Pt; a water-soluble compound of the alkaline earth metal; An S-containing water-soluble organic compound containing S and capable of forming a sulfate of the alkaline earth metal is mixed with an aqueous solvent to prepare a raw material suspension.
Next, the raw material suspension is dried and further calcined to prepare a powder material in which the porous carrier, Pt, and an alkaline earth metal sulfate are mixed.
Then, a slurry for forming an alkaline earth metal-supported region containing at least the powder material and an aqueous solvent is prepared.
Thereafter, the alkaline earth metal supporting region is formed on the base material using the slurry.
使用する材料について、多孔質担体を構成する無機化合物の例としては、上記と同様である。
Ｐｔを析出させるための前駆物質としては、例えばＰｔの水溶性の錯体や塩が挙げられる。
アルカリ土類金属の水溶性化合物としては、種々の塩、例えばＢａ、ＳｒまたはＣａの水酸化物、ハロゲン化物、酢酸塩、硝酸塩、亜硝酸塩等が挙げられる。水に対する溶解度が高いもの（例えば、酢酸塩、亜硝酸塩、およびヨウ化物、特に、酢酸バリウム、亜硝酸バリウム、およびヨウ化バリウム）が特に好ましい。
Ｓ含有水溶性有機化合物としては、上記原料懸濁物を調製し、乾燥、焼成する過程においてアルカリ土類金属の硫酸塩を形成し得るものであれば特に制限はない。好適例として、タウリン（２−アミノエタンスルホン酸）、アミノベンゼンスルホン酸、アミノメタンスルホン酸、１−アミノ−２−ナフトール−４−スルホン酸、システイン酸、メチオニン、シスチン、硫酸ジメチル、ジメチルスルフィド、ジメチルトリスルフィド、２−メルカプトエタノール、ジフェニルスルフィド、ジチオトレイトール、二硫化アリル、スルホラン、フルフリルメルカプタン、ジプロピルジスルフィド、ジメチルスルホン、ジメチルスルホキシド、等が挙げられる。
これらのうち、分子内にスルホ基（−ＳＯ３Ｈ）、スルホニル基（−Ｓ（＝Ｏ）２−）、スルフィニル基（−Ｓ（＝Ｏ）−）のうちの何れか少なくとも一つの官能基を有する水溶性有機物の使用が硫酸塩の生成のための反応性がよく、好適である。
また、アミノ基（−ＮＨ２）等の塩基性基を有するものは、原料懸濁物のｐＨの低下（即ち強酸性化）を防止する効果が高いため、好ましい。
また、劇物、毒物に指定されておらず扱いが容易であること、水に対する溶解度が特に高いこと、分子内にスルホン酸基とアミノ基とを有するために硫酸塩調製時のｐＨ変動が特に小さいことから、タウリン（２−アミノエタンスルホン酸）、アミノベンゼンスルホン酸、アミノメタンスルホン酸、１−アミノ−２−ナフトール−４−スルホン酸、システイン酸、メチオニン、シスチンが特に好ましい。
Regarding the materials to be used, examples of the inorganic compound constituting the porous carrier are the same as those described above.
Examples of the precursor for depositing Pt include a water-soluble complex or salt of Pt.
Examples of the water-soluble compound of an alkaline earth metal include various salts, for example, hydroxides, halides, acetates, nitrates, and nitrites of Ba, Sr or Ca. Those with high water solubility (eg, acetates, nitrites, and iodides, particularly barium acetate, barium nitrite, and barium iodide) are particularly preferred.
The S-containing water-soluble organic compound is not particularly limited as long as it can form a sulfate of an alkaline earth metal in the process of preparing the above-mentioned raw material suspension, drying and baking. As preferred examples, taurine (2-aminoethanesulfonic acid), aminobenzenesulfonic acid, aminomethanesulfonic acid, 1-amino-2-naphthol-4-sulfonic acid, cysteic acid, methionine, cystine, dimethyl sulfate, dimethylsulfide, Examples include dimethyl trisulfide, 2-mercaptoethanol, diphenyl sulfide, dithiothreitol, allyl disulfide, sulfolane, furfuryl mercaptan, dipropyl disulfide, dimethyl sulfone, and dimethyl sulfoxide.
Among these, at least one functional group of a sulfo group (—SO 3 H), a sulfonyl group (—S (＝ O) 2 —), and a sulfinyl group (—S (＝ O) —) is present in the molecule. The use of a water-soluble organic substance having the following is preferred because of its high reactivity for the production of sulfate.
Further, those having a basic group such as an amino group (—NH 2 ) are preferable because they have a high effect of preventing a decrease in the pH of the raw material suspension (that is, strong acidification).
In addition, it is easy to handle because it is not specified as a deleterious substance or poison, has a particularly high solubility in water, and has a sulfonic acid group and an amino group in the molecule, so that pH fluctuation during the preparation of sulfate is particularly high. Due to their small size, taurine (2-aminoethanesulfonic acid), aminobenzenesulfonic acid, aminomethanesulfonic acid, 1-amino-2-naphthol-4-sulfonic acid, cysteic acid, methionine, and cystine are particularly preferred.
具体的な操作としては、上述した各種材料（無機化合物粒子、Ｐｔ粒子またはＰｔを析出させるための前駆物質、アルカリ土類金属の水溶性化合物、Ｓ含有水溶性有機化合物）を水系溶媒（典型的には水、例えば純水や脱イオン水）に添加し、攪拌機を用いてよく攪拌することにより、スラリー状の原料懸濁物を調製することができる。例えば、最初にＰｔ粒子またはＰｔを析出させるための前駆物質を水に懸濁させ、得られた懸濁液に多孔質担体を構成する無機化合物粒子（粉末）を混合して攪拌し、さらにアルカリ土類金属の水溶性化合物を添加して所定時間（例えば１０分〜６０分間）よく攪拌し、その後、Ｓ含有水溶性有機化合物を添加して、９０〜１３０℃程度の温度域で十分に（例えば６時間以上、好適には８時間以上）乾燥させ、さらに４００〜６００℃程度の温度域で数時間（例えば１〜３時間程度）かけて焼成する。
このようなプロセスによって、触媒層（アルカリ土類金属担持領域を含む）を形成する前段階で、多孔質担体粒子（二次粒子）の外表面および内部（細孔内）に高度に分散した状態でＰｔおよびアルカリ土類金属硫酸塩が担持（固定）された粉末材料を調製することができる。得られた粉末材料は、必要に応じて粉砕処理に供し、所望の粒子サイズ（例えば粒径が１０μｍ以下）に調整することができる。
As a specific operation, the above-mentioned various materials (inorganic compound particles, Pt particles or a precursor for precipitating Pt, a water-soluble compound of an alkaline earth metal, a water-soluble organic compound containing S) are mixed with an aqueous solvent (typical). (Water, for example, pure water or deionized water), and sufficiently stirred using a stirrer to prepare a slurry-like raw material suspension. For example, first, Pt particles or a precursor for precipitating Pt are suspended in water, and the obtained suspension is mixed with inorganic compound particles (powder) constituting the porous carrier, stirred, and further mixed with alkali. The water-soluble compound of the earth metal is added and stirred well for a predetermined time (for example, 10 minutes to 60 minutes). Then, the S-containing water-soluble organic compound is added and sufficiently added in a temperature range of about 90 to 130 ° C. For example, drying is performed for 6 hours or more, preferably 8 hours or more), and firing is performed for several hours (for example, about 1 to 3 hours) in a temperature range of about 400 to 600 ° C.
By such a process, prior to the formation of the catalyst layer (including the alkaline earth metal-supported region), the porous carrier particles (secondary particles) are highly dispersed on the outer surface and inside (in the pores). Can prepare a powder material in which Pt and alkaline earth metal sulfate are supported (fixed). The obtained powder material can be subjected to a pulverizing treatment as needed to adjust to a desired particle size (for example, a particle size of 10 μm or less).
かかるプロセスによると、多孔質担体粒子の外表面および細孔内に担持されるアルカリ土類金属硫酸塩の粒径を従来よりも極めて小さいものとすることができる。
典型的には、ここで開示される技術によると、Ｘ線回折法に基づく平均粒径が３０ｎｍ以下（例えば１０ｎｍ以上３０ｎｍ以下）、好ましくは２０ｎｍ以下であるような微細なアルカリ土類金属硫酸塩（例えば硫酸バリウム）粒子を、多孔質担体粒子の外表面および細孔内に高度な分散状態で担持させることができる。
そして、上記プロセスによると、上記相関係数：ＲＡｅ／Ｐｔが０．５以上、さらには０．６以上、またさらには０．７以上であるような、高度な分散状態を実現することができる。
According to such a process, the particle size of the alkaline earth metal sulfate carried on the outer surface and in the pores of the porous carrier particles can be made much smaller than before.
Typically, according to the technology disclosed herein, fine alkaline earth metal sulfates having an average particle size based on X-ray diffraction of 30 nm or less (for example, 10 nm or more and 30 nm or less), preferably 20 nm or less. (For example, barium sulfate) particles can be supported in a highly dispersed state on the outer surface and in the pores of the porous carrier particles.
According to the above process, it is possible to realize a highly dispersed state in which the correlation coefficient: R Ae / Pt is 0.5 or more, further 0.6 or more, and further 0.7 or more. it can.
次に、得られた上記粉末材料（適宜に粉砕処理を施したもの）を用いて、触媒層（アルカリ土類金属担持領域）形成用のスラリーを調製する。かかるスラリーの調製は、従来の排ガス浄化用触媒の触媒層を形成する場合と同様でよく、特別な制限はない。
例えば、図２に示すような上下二層構造タイプの触媒層６の構成が相互に異なる排ガス浄化用触媒１０の基材１上にアルカリ土類金属担持領域である上層６Ａを形成する場合、所望の触媒金属成分（Ｐｔ以外の触媒金属イオン（例、Ｒｈ）を含む溶液）と、所望の担体粉末（アルミナ、ジルコニア、ＣＺ複合酸化物からなるＯＳＣ材、等）とを含む下層形成用スラリーをウォッシュコート法等によってハニカム基材１にコートする。
次いで、上記調製した粉末材料と、さらに必要に応じて、アルカリ土類金属が担持されていない担体粉末（例えば、アルミナやジルコニア、或いはＣＺ複合酸化物等のＯＳＣ材）と、を含むアルカリ土類金属担持領域形成用スラリーを公知のウォッシュコート法等によって下層６Ｂの表面に積層コートする。
或いは、このような一度の焼成プロセスに代えて、下層形成用スラリーをハニカム基材１にコートした後、所定の温度及び時間で乾燥し焼成することによって、先ず下層を形成し、次いで、アルカリ土類金属担持領域形成用スラリーを下層の表面にコートして乾燥及び焼成を行って触媒層の上層を形成する二段階の焼成を行うプロセスでもよい。
Next, a slurry for forming a catalyst layer (alkaline earth metal supporting region) is prepared using the obtained powder material (which has been appropriately pulverized). The preparation of such a slurry may be the same as the case of forming a catalyst layer of a conventional exhaust gas purifying catalyst, and there is no particular limitation.
For example, when the upper layer 6A, which is an alkaline-earth metal supporting region, is formed on the base material 1 of the exhaust gas purifying catalyst 10 in which the structure of the upper and lower two-layer structure type catalyst layer 6 shown in FIG. And a lower layer forming slurry containing a catalyst metal component (a solution containing a catalyst metal ion other than Pt (eg, Rh)) and a desired carrier powder (alumina, zirconia, OSC material composed of CZ composite oxide, etc.) The honeycomb substrate 1 is coated by a wash coat method or the like.
Next, an alkaline earth containing the powder material prepared above and, if necessary, a carrier powder not supporting an alkaline earth metal (for example, an OSC material such as alumina, zirconia, or CZ composite oxide). The surface of the lower layer 6B is laminated and coated with the slurry for forming the metal supporting region by a known wash coating method or the like.
Alternatively, instead of such a one-time baking process, the lower layer forming slurry is coated on the honeycomb substrate 1 and then dried and fired at a predetermined temperature and time to form the lower layer first, and then the alkaline earth A process in which the slurry for forming a metal-like supporting region is coated on the surface of the lower layer, followed by drying and firing to form an upper layer of the catalyst layer, and a two-stage firing process may be employed.
ウォッシュコートされたスラリーの焼成条件は基材または担体の形状及びサイズによっても変動するので特に限定しないが、典型的には４００〜１０００℃程度で約１〜５時間程度の焼成を行うことによって、目的のアルカリ土類金属担持領域および他の領域の触媒層を形成することができる。また、焼成前の乾燥条件については特に限定されるものではないが、８０〜３００℃の温度で１〜１２時間程度の乾燥が好ましい。
また、触媒層６をウォッシュコート法により形成する場合、基材１の表面、さらに積層構造触媒層の場合には下層６Ｂの表面にスラリーを好適に密着させるため、スラリーにはバインダーを含有させることが好ましい。かかる目的のバインダーとしては、例えばアルミナゾル、シリカゾル等の使用が好ましい。なお、スラリーの粘度は当該スラリーが基材（例えばハニカム基材）１のセル２内へ容易に流入し得るように適宜調整するとよい。
The firing conditions of the wash-coated slurry are not particularly limited because they vary depending on the shape and size of the base material or the carrier, but typically, by firing at about 400 to 1000 ° C. for about 1 to 5 hours, It is possible to form the catalyst layer in the target alkaline earth metal supporting region and other regions. The drying conditions before firing are not particularly limited, but drying at a temperature of 80 to 300 ° C. for about 1 to 12 hours is preferable.
When the catalyst layer 6 is formed by the wash coat method, a binder should be contained in the slurry so that the slurry can be appropriately adhered to the surface of the base material 1 and, in the case of a laminated catalyst layer, to the surface of the lower layer 6B. Is preferred. As the binder for this purpose, for example, use of alumina sol, silica sol or the like is preferable. The viscosity of the slurry may be appropriately adjusted so that the slurry can easily flow into the cells 2 of the base material (for example, the honeycomb base material) 1.
以下、本発明に関するいくつかの実施例につき説明するが、本発明をかかる具体例に示すものに限定することを意図したものではない。 Hereinafter, some examples of the present invention will be described, but the present invention is not intended to be limited to the specific examples.
＜試験例１：排ガス浄化用触媒の作製＞
本試験例では、図１に示すような直径：１０３ｍｍ、全長：１０５ｍｍである円筒形状のハニカム基材（即ち触媒容積が０．８７５Ｌのコージェライト製ハニカム基材）を使用し、図２に示すような二層構造触媒層を備える排ガス浄化用触媒を以下のとおり作製した。
<Test Example 1: Preparation of exhaust gas purifying catalyst>
In this test example, a cylindrical honeycomb substrate having a diameter of 103 mm and a total length of 105 mm as shown in FIG. 1 (that is, a cordierite honeycomb substrate having a catalyst volume of 0.875 L) is used and shown in FIG. An exhaust gas purifying catalyst having such a two-layer catalyst layer was produced as follows.
（実施例１）
Ｐｔ量で１７．５ｇのジニトロジアンミン白金を純水１Ｌに添加し、撹拌して懸濁液を作製した。この懸濁液にアルミナ７４０ｇを添加した後、酢酸バリウム７２ｇを添加して、攪拌した。その後、タウリン７０ｇを添加し、撹拌してスラリー状の原料懸濁物を作製した。
この原料懸濁物を、１１０℃で８時間以上乾燥し、続いて５００℃で２時間焼成した。その後、粒径が１０μｍ以下になるまで適当な粉砕処理を施すことにより、Ｐｔ含有粉末材料を作製した。
(Example 1)
17.5 g of dinitrodiammineplatinum in Pt amount was added to 1 L of pure water and stirred to prepare a suspension. After adding 740 g of alumina to this suspension, 72 g of barium acetate was added and stirred. Thereafter, 70 g of taurine was added and stirred to prepare a slurry-like raw material suspension.
This raw material suspension was dried at 110 ° C. for 8 hours or more, and subsequently calcined at 500 ° C. for 2 hours. Thereafter, a suitable pulverizing treatment was performed until the particle diameter became 10 μm or less, thereby producing a Pt-containing powder material.
次に、上記作製したＰｔ含有粉末材料と、Ｃｅの含有量が３０重量％であるＣＺ複合酸化物粉末１８００ｇと、アルミナバインダー８７ｇとを、純水３．６Ｌに添加し、磁性ボールミルを用いて湿式粉砕を行うことによって、上層形成用スラリーを調製した。
一方、Ｒｈ量で５．６ｇの硝酸ロジウムを純水０．９Ｌに懸濁させた。得られた懸濁液に、ジルコニア粉末８０３ｇを添加し、乾燥し、続いて５００℃で２時間焼成した。その後、粒径が１０μｍ以下になるまで適当な粉砕処理を施すことにより、Ｒｈ含有粉末材料を作製した。このＲｈ含有粉末材料に対して、アルミナ粉末４１５ｇと、Ｃｅの含有量が２０重量％であるＣＺ複合粉末４１３ｇと、アルミナバインダー６１ｇとを純水２．３Ｌに添加し、磁性ボールミルを用いて湿式粉砕を行うことによって、下層形成用スラリーを調製した。
Next, the above-prepared Pt-containing powder material, 1800 g of a CZ composite oxide powder having a Ce content of 30% by weight, and 87 g of an alumina binder were added to 3.6 L of pure water, and the mixture was added using a magnetic ball mill. The slurry for upper layer formation was prepared by performing wet grinding.
On the other hand, 5.6 g of rhodium nitrate in Rh amount was suspended in 0.9 L of pure water. To the obtained suspension, 803 g of zirconia powder was added, dried, and subsequently calcined at 500 ° C. for 2 hours. Thereafter, an appropriate pulverization treatment was performed until the particle diameter became 10 μm or less, thereby producing a Rh-containing powder material. To this Rh-containing powder material, 415 g of alumina powder, 413 g of CZ composite powder having a Ce content of 20% by weight, and 61 g of alumina binder were added to 2.3 L of pure water, and wet-processed using a magnetic ball mill. By grinding, a slurry for forming a lower layer was prepared.
先ず下層形成用スラリーを用いて基材に対してウォッシュコートを施し、１５０℃で１時間ほど乾燥することにより、基材の表面（セル内のリブ壁面）に下層（非焼成コート層）を形成した。次いで、上層形成用スラリーを用いて基材に対してウォッシュコートを施し、１５０℃で１時間ほど乾燥することにより下層の表面に上層（非焼成コート層）を積層形成した。その後、５００℃で１時間の焼成を行い、上下二層からなる触媒層（コート量は上下層あわせて２２０ｇ／Ｌとした）が形成された排ガス浄化用触媒を得た。 First, a wash coat is applied to the base material using the slurry for forming the lower layer, and dried at 150 ° C. for about 1 hour to form a lower layer (non-fired coat layer) on the surface of the base material (the rib wall surface in the cell). did. Next, a wash coat was applied to the substrate using the slurry for forming an upper layer, and dried at 150 ° C. for about 1 hour to form an upper layer (non-fired coat layer) on the surface of the lower layer. Thereafter, baking was performed at 500 ° C. for 1 hour to obtain an exhaust gas purifying catalyst on which a catalyst layer composed of upper and lower layers (coat amount was 220 g / L for both upper and lower layers) was formed.
（実施例２）
Ｐｔ含有粉末材料を作製する際に、原料懸濁物を１１０℃で８時間以上乾燥する代わりに３０℃で４８時間乾燥した以外は実施例１と同様にして排ガス浄化用触媒を得た。
(Example 2)
An exhaust gas purifying catalyst was obtained in the same manner as in Example 1 except that the raw material suspension was dried at 30 ° C. for 48 hours instead of drying the raw material suspension at 110 ° C. for 8 hours or more when producing the Pt-containing powder material.
（比較例１）
Ｐｔ含有粉末材料を作製する際に、Ｂａ源として酢酸バリウム７２ｇの代わりに硫酸バリウム６６ｇを使用し、Ｂａ固定化材であるタウリンを添加しなかった以外は実施例１と同様にして排ガス浄化用触媒を得た。
(Comparative Example 1)
When producing a Pt-containing powder material, for purifying exhaust gas in the same manner as in Example 1, except that 66 g of barium sulfate was used instead of 72 g of barium acetate as a Ba source, and taurine as a Ba fixing material was not added. A catalyst was obtained.
（比較例２）
Ｐｔ含有粉末材料を作製する際に、Ｂａ固定化材であるタウリン７０ｇの代わりに無機化合物である硫酸アンモニウム７４ｇを使用した以外は実施例１と同様にして排ガス浄化用触媒を得た。
(Comparative Example 2)
An exhaust gas purifying catalyst was obtained in the same manner as in Example 1 except that when preparing the Pt-containing powder material, 74 g of ammonium sulfate as an inorganic compound was used instead of 70 g of taurine as a Ba fixing material.
（比較例３）
Ｐｔ含有粉末材料を作製する際に、Ｂａ固定化材であるタウリンを添加しなかった以外は実施例１と同様にして排ガス浄化用触媒を得た。
(Comparative Example 3)
An exhaust gas purifying catalyst was obtained in the same manner as in Example 1 except that Taurine, which was a Ba fixing material, was not added when producing the Pt-containing powder material.
＜試験例２：Ｐｔ含有粉末材料のＦＥ−ＥＰＭＡによる硫酸バリウムの分散性の確認＞
日本電子株式会社製のＦＥ−ＥＰＭＡ装置（ＪＸＡ−８５３０Ｆ）をマニュアルどおりに使用し、試験例１で作製した各Ｐｔ含有粉末材料について面分析を行った。
即ち、所定量の各粉末材料の表面を研磨して断面を出し、市販のカーボンコーター（株式会社真空デバイス製品：ＶＣ−１００Ｗ）を使用して導電性物質としての炭素を蒸着した。そして、炭素蒸着面のうちのＰｔ含有粉末材料に該当する領域を適宜定め、かかる領域に対してＦＥ−ＥＰＭＡによる面分析を行った。測定条件は、
ピクセルサイズ：０．３４μｍ×０．３４μｍ、
測定ピクセル数：２５６×２５６、
加速電圧：２０ｋＶ、
照射電流：１００ｎＡ、
プローブ径：当該測定条件における最小に設定、
単位測定時間：５０ｍｓ／１ピクセル、
測定倍率：×１０００
とした。そして、ピクセル毎にＢａ元素の特性Ｘ線の強度（α：ｃｐｓ）およびＰｔの特性Ｘ線の強度（β：ｃｐｓ）を測定した。
なお、かかる面分析において、１ピクセル（区域）あたりのＸ線強度の閾値をＢａでは１５ｃｐｓ、Ｐｔでは５ｃｐｓと設定し、閾値以下の強度を示したピクセルは、相関係数の算出のためのデータから除外した。
<Test Example 2: Confirmation of barium sulfate dispersibility of Pt-containing powder material by FE-EPMA>
Using a FE-EPMA device (JXA-8530F) manufactured by JEOL Ltd. according to the manual, surface analysis was performed on each Pt-containing powder material produced in Test Example 1.
That is, the surface of each powder material of a predetermined amount was polished to obtain a cross section, and carbon as a conductive substance was deposited using a commercially available carbon coater (Vacuum Device Co., Ltd .: VC-100W). Then, a region corresponding to the Pt-containing powder material on the carbon vapor-deposited surface was appropriately determined, and the region was subjected to surface analysis by FE-EPMA. The measurement conditions are
Pixel size: 0.34 μm × 0.34 μm,
Measurement pixels: 256 × 256,
Acceleration voltage: 20 kV,
Irradiation current: 100 nA,
Probe diameter: set to the minimum under the relevant measurement conditions,
Unit measurement time: 50 ms / 1 pixel,
Measurement magnification: × 1000
And The characteristic X-ray intensity of Ba element (α: cps) and the characteristic X-ray intensity of Pt (β: cps) were measured for each pixel.
In this surface analysis, the threshold value of the X-ray intensity per pixel (area) is set to 15 cps for Ba and 5 cps for Pt, and the pixels showing the intensity lower than the threshold value are data for calculating the correlation coefficient. Excluded from.
こうして面分析を行い、得られたデータを表計算ソフト「エクセル」のCORREL関数機能を用いて相関係数ＲＢａ／Ｐｔを求めた。結果を表１に示す。
また、実施例１の試料、および比較例１〜２の試料については、ＢａとＳの元素マッピングについてのデータ（画像）を図３〜６に示す。
The surface analysis was performed in this manner, and the obtained data was used to determine a correlation coefficient RBa / Pt using the CORREL function function of spreadsheet software "Excel". Table 1 shows the results.
FIGS. 3 to 6 show data (images) on element mapping of Ba and S for the sample of Example 1 and the samples of Comparative Examples 1 and 2. FIG.
＜試験例３：Ｂａ溶出性試験＞
試験例１で作製した各Ｐｔ含有粉末材料を、純水に懸濁させ、酸を添加したときのＢａの溶出量を、アジレント社製ＩＣＰ発光分光分析装置（Ａｇｉｌｅｎｔ５１１０ ＩＣＰ−ＯＥＳ）により測定し、Ｂａ溶出率を求めた。結果を表１に示す。
<Test Example 3: Ba dissolution test>
Each Pt-containing powder material produced in Test Example 1 was suspended in pure water, and the amount of Ba eluted when an acid was added was measured by an ICP emission spectrometer (Agilent 5110 ICP-OES) manufactured by Agilent. The Ba elution rate was determined. Table 1 shows the results.
表１および図３〜６の結果より、比較例１および２では、Ｂａが担体二次粒子の外部に凝集しているのに対して、実施例１では担体二次粒子内部にＢａが高度に分散して担持されていることがわかる。
相関係数の値が０．５以上では強い相関、０．７以上では特に強い相関があると解釈されるが、実施例１では、相関係数ＲＢａ／Ｐｔの値が０．７９８であり、Ｐｔの存在位置とＢａの存在位置に特に強い相関があることが認められる。
一方、比較例１および比較例２では、相関係数ＲＢａ／Ｐｔの値はそれぞれ−０．１２８、０．０６０であり、ＰｔとＢａの存在位置に相関関係は認められない。
このことから、比較例１および２に比べて実施例１では、Ｂａが高度に分散しているだけでなく、ＰｔとＢａが近接していることがわかる。
比較例３では、相関係数ＲＢａ／Ｐｔの値が０．７２０と、ＰｔとＢａの存在位置に強い相関が認められるが、Ｂａ溶出率が７０％であり、Ｂａを固定化することができなかった。
From the results of Table 1 and FIGS. 3 to 6, in Comparative Examples 1 and 2, Ba was agglomerated outside the secondary particles of the carrier, whereas in Example 1, Ba was highly concentrated inside the secondary particles of the carrier. It can be seen that they are dispersed and supported.
If the value of the correlation coefficient is 0.5 or more, it is interpreted that there is a strong correlation, and if the value of the correlation coefficient is 0.7 or more, it is interpreted that there is a particularly strong correlation. In Example 1, the value of the correlation coefficient RBa / Pt is 0.798. , Pt and the position of Ba have a particularly strong correlation.
On the other hand, in Comparative Examples 1 and 2, the values of the correlation coefficient RBa / Pt are -0.128 and 0.060, respectively, and there is no correlation between the positions of Pt and Ba.
From this, it can be seen that in Example 1, as compared with Comparative Examples 1 and 2, Ba is not only highly dispersed but also Pt and Ba are close to each other.
In Comparative Example 3, the value of the correlation coefficient RBa / Pt was 0.720, and a strong correlation was observed between the positions of Pt and Ba. However, the Ba elution rate was 70%, and Ba was immobilized. could not.
＜試験例４：Ｐｔ含有粉末材料のＨＣ浄化率測定＞
実施例１および比較例１で用いたＰｔ含有粉末材料のペレットを作製し、管状炉を用いてＲｉｃｈ／Ｌｅａｎ耐久を行った。その後、ベスト測機社製活性評価装置（ＣＡＴＡ５０００）を用いて空燃比をＬｅａｎからＲｉｃｈに切り替えてから３分後のＨＣ浄化率を測定した。結果を図７に示す。
<Test Example 4: HC purification rate measurement of Pt-containing powder material>
Pellets of the Pt-containing powder material used in Example 1 and Comparative Example 1 were prepared, and subjected to Rich / Lean durability using a tubular furnace. Thereafter, the HC purification rate was measured 3 minutes after the air-fuel ratio was switched from Lean to Rich using an activity evaluation device (CATA5000) manufactured by Best Sokki Co., Ltd. FIG. 7 shows the results.
図７が示すように、実施例１で用いたＰｔ含有粉末材料の方がはるかに高いＨＣ浄化率を示した。
実施例１では、Ｂａが担体二次粒子に高分散担持されており、ＰｔとＢａの存在位置に相関が認められるほどにＰｔとＢａが近接化されている。このため、Ｐｔに対するＢａの電子供与によりＨＣ被毒抑制が起こり、Ｒｉｃｈ雰囲気時のＨＣ浄化性能が向上したものと考えられる。
As shown in FIG. 7, the Pt-containing powder material used in Example 1 showed a much higher HC purification rate.
In Example 1, Ba is highly dispersed and supported on the carrier secondary particles, and Pt and Ba are brought close to each other so that a correlation is found between the positions of Pt and Ba. For this reason, it is considered that HC poisoning was suppressed by the electron donation of Ba to Pt, and the HC purification performance in the Rich atmosphere was improved.
＜試験例５：Ｒｈ含有触媒層のＦＥ−ＥＰＭＡによる評価＞
実施例１で作製した排ガス浄化用触媒の上層触媒層と下層触媒層の積層部を切り出し、断面を研磨した。断面に市販のカーボンコーター（株式会社真空デバイス製品：ＶＣ−１００Ｗ）を使用して導電性物質としての炭素を蒸着した。この断面について、上記のＦＥ−ＥＰＭＡ装置（ＪＸＡ−８５３０Ｆ）を用いて、面分析を行った。測定条件は、
ピクセルサイズ：０．８５μｍ×０．８５μｍ、
測定ピクセル数：２５６×２５６、
加速電圧：２０ｋＶ、
照射電流：１００ｎＡ、
プローブ径：当該測定条件における最小に設定、
単位測定時間：５０ｍｓ／１ピクセル、
測定倍率：×４００
とした。そして、ピクセル毎にＢａ元素の特性Ｘ線の強度（α：ｃｐｓ）およびＲｈの特性Ｘ線の強度（β：ｃｐｓ）を測定した。
なお、かかる面分析において、１ピクセル（区域）あたりのＸ線強度の閾値をＢａでは１５ｃｐｓ、Ｒｈでは５ｃｐｓと設定し、閾値以下の強度を示したピクセルは、相関係数の算出のためのデータから除外した。
得られたデータを表計算ソフト「エクセル」のCORREL関数機能を用いて相関係数ＲＢａ／Ｒｈを求めた。
その結果、相関係数ＲＢａ／Ｒｈは、０．０２３であり、ＢａとＲｈの触媒中における存在位置に相関関係は認められなかった。このことから、実施例１の排ガス浄化用触媒では、Ｐｔを含有するアルカリ土類金属担持領域である上層においてＢａが固定化されていることにより、上層に存在するＢａと下層に存在するＲｈとの接触を防止できていることがわかる。
<Test Example 5: Evaluation of Rh-containing catalyst layer by FE-EPMA>
The laminated portion of the upper catalyst layer and the lower catalyst layer of the exhaust gas purifying catalyst produced in Example 1 was cut out and the cross section was polished. Carbon as a conductive material was vapor-deposited on the cross section using a commercially available carbon coater (Vacuum Device Co., Ltd .: VC-100W). This cross section was subjected to surface analysis using the above-mentioned FE-EPMA apparatus (JXA-8530F). The measurement conditions are
Pixel size: 0.85 μm × 0.85 μm,
Measurement pixels: 256 × 256,
Acceleration voltage: 20 kV,
Irradiation current: 100 nA,
Probe diameter: set to the minimum under the relevant measurement conditions,
Unit measurement time: 50 ms / 1 pixel,
Measurement magnification: × 400
And Then, the intensity of the characteristic X-ray of the Ba element (α: cps) and the intensity of the characteristic X-ray of Rh (β: cps) were measured for each pixel.
In this surface analysis, the threshold value of the X-ray intensity per pixel (area) is set to 15 cps for Ba and 5 cps for Rh, and the pixels showing the intensity lower than the threshold value are the data for calculating the correlation coefficient. Excluded from.
The correlation coefficient RBa / Rh of the obtained data was determined using the CORREL function function of spreadsheet software "Excel".
As a result, the correlation coefficient RBa / Rh was 0.023, and no correlation was found between the positions of Ba and Rh in the catalyst. From this, in the exhaust gas purifying catalyst of Example 1, Ba is fixed in the upper layer which is the alkaline earth metal supporting region containing Pt, so that Ba present in the upper layer and Rh present in the lower layer are reduced. It can be seen that the contact of the object was prevented.
＜試験例６：排ガス浄化用触媒の浄化率測定＞
実施例１および比較例１で作製した排ガス浄化用触媒をエンジンの排気系に設置し、エンジンを稼働させ耐久を行った。
かかる耐久試験後、その触媒を用いてエンジンに供給する混合ガスの空燃比をＬｅａｎからＲｉｃｈに切り替えてから３分後のＨＣ浄化率およびＮＯｘ浄化率を測定した。結果を図８および図９に示す。
<Test Example 6: Measurement of Purification Rate of Exhaust Gas Purification Catalyst>
The exhaust gas purifying catalysts produced in Example 1 and Comparative Example 1 were installed in an exhaust system of an engine, and the engine was operated to perform durability.
After such durability test were measured HC purification ratio and the NO x purification ratio after 3 minutes after switching on Rich fuel ratio of the gas mixture supplied to the engine from the Lean using the catalyst. The results are shown in FIGS.
図８および図９の結果が示すように、実施例１の排ガス浄化用触媒は、比較例１の排ガス浄化用触媒よりもはるかに高いＨＣ浄化率およびＮＯｘ浄化率を示した。この理由は次のように考えられる。
実施例１では、Ｂａが担体二次粒子に高分散担持されているため、ＰｔとＢａの存在位置に相関が認められるほどにＰｔとＢａとが近接化されている。このため、Ｐｔに対するＢａの電子供与によりＨＣ被毒抑制が起こり、Ｒｉｃｈ雰囲気時のＨＣ浄化性能が向上する。さらにＢａが固定化されていることにより、ＢａとＲｈとの接触が防止されており、これにより、ＢａによるＲｈのメタル化抑制が防止されている。さらに、上流のＰｔ含有触媒層のＨＣ浄化作用が向上することによって下流のＲｈ含有触媒層へ流入するＨＣ量が減少することにより、Ｒｈの被毒が抑制される。以上のことから共存ＮＯｘの浄化性能も向上する。
As shown in the results of FIG. 8 and FIG. 9, the exhaust gas purifying catalyst of Example 1 showed much higher HC purification ratio and the NO x purification rate than the exhaust gas purifying catalyst of Comparative Example 1. The reason is considered as follows.
In Example 1, since Ba is highly dispersed and supported on the carrier secondary particles, Pt and Ba are brought close to each other such that a correlation is found between the positions of Pt and Ba. For this reason, HC poisoning is suppressed by the electron donation of Ba to Pt, and the HC purification performance in the Rich atmosphere is improved. Further, since Ba is immobilized, contact between Ba and Rh is prevented, and thereby, suppression of metalization of Rh by Ba is prevented. Furthermore, the poisoning of Rh is suppressed by reducing the amount of HC flowing into the downstream Rh-containing catalyst layer by improving the HC purification action of the upstream Pt-containing catalyst layer. Also improves purification performance of coexistence NO x from the above.
以上、本発明の具体例を詳細に説明したが、これらは例示にすぎず、請求の範囲を限定するものではない。請求の範囲に記載の技術には、以上に例示した具体例を様々に変形、変更したものが含まれる。 As mentioned above, although the specific example of this invention was demonstrated in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
１ 基材
２ セル
４ 隔壁
６ 触媒層
６Ａ 上層
６Ｂ 下層
１０ 排ガス浄化用触媒
DESCRIPTION OF SYMBOLS 1 Base material 2 Cell 4 Partition wall 6 Catalyst layer 6A Upper layer 6B Lower layer 10 Exhaust gas purification catalyst
Claims (8)
基材と、
当該基材上に形成された触媒層と、
を備えており、
前記触媒層は、
無機化合物から構成される多孔質担体と、
前記多孔質担体に担持されたＰｔと、
前記多孔質担体に担持された、少なくとも一種のアルカリ土類金属の硫酸塩と、
を備えるアルカリ土類金属担持領域を有しており、
ここで、前記触媒層のアルカリ土類金属担持領域の断面について、
ピクセルサイズ ０．３４μｍ×０．３４μｍ；
測定ピクセル数 ２５６×２５６；
の条件でＦＥ−ＥＰＭＡによる面分析を行い、前記アルカリ土類金属の元素（Ａｅ）の特性Ｘ線の強度（α：ｃｐｓ）およびＰｔの特性Ｘ線の強度（β：ｃｐｓ）を各ピクセルについて測定し、得られた各ピクセルにおけるαおよびβを用いて算出したピアソンの相関係数をＲＡｅ／Ｐｔとしたとき、
当該ＲＡｅ／Ｐｔの値が０．５以上であることを特徴とする、排ガス浄化用触媒。 An exhaust gas purifying catalyst disposed in an exhaust pipe of an internal combustion engine to purify exhaust gas discharged from the internal combustion engine,
A substrate,
A catalyst layer formed on the substrate,
With
The catalyst layer,
A porous carrier composed of an inorganic compound,
Pt supported on the porous carrier;
Supported on the porous carrier, at least one sulfate of an alkaline earth metal,
Having an alkaline earth metal carrying region comprising
Here, regarding the cross section of the alkaline earth metal supporting region of the catalyst layer,
Pixel size 0.34 μm × 0.34 μm;
Number of measured pixels 256 × 256;
The surface analysis by FE-EPMA is performed under the following conditions, and the characteristic X-ray intensity (α: cps) of the alkaline earth metal element (Ae) and the characteristic X-ray intensity (β: cps) of Pt are determined for each pixel. When the Pearson's correlation coefficient calculated using the measured and obtained α and β in each pixel is defined as RAe / Pt ,
An exhaust gas purifying catalyst, wherein the value of R Ae / Pt is 0.5 or more.
基材上に、
無機化合物から構成される多孔質担体と、
当該多孔質担体に担持されたＰｔと、
当該多孔質担体に担持された少なくとも一種のアルカリ土類金属の硫酸塩と、
を備えるアルカリ土類金属担持領域を少なくとも一部に有する触媒層を形成する工程、および
前記触媒層が形成された基材を焼成する工程、
を包含し、
ここで、前記触媒層の形成工程は、
以下の成分：
前記多孔質担体を構成する無機化合物粒子；
Ｐｔ粒子またはＰｔを析出させるための前駆物質；
前記アルカリ土類金属の水溶性化合物；および
構成元素としてＳを含有し、前記アルカリ土類金属の硫酸塩を生成可能なＳ含有水溶性有機化合物；
を水系溶媒と混合し、原料懸濁物を調製すること、
前記原料懸濁物を乾燥し、さらに焼成することによって、前記多孔質担体とＰｔとアルカリ土類金属の硫酸塩とが混在する粉末材料を調製すること、
少なくとも前記粉末材料と水系溶媒を含むアルカリ土類金属担持領域形成用スラリーを調製すること、および
前記スラリーを用いて前記基材上に前記アルカリ土類金属担持領域を形成すること、
を包含する、排ガス浄化用触媒の製造方法。 A method for producing an exhaust gas purifying catalyst that is disposed in an exhaust pipe of an internal combustion engine and purifies exhaust gas discharged from the internal combustion engine,
On the substrate,
A porous carrier composed of an inorganic compound,
Pt supported on the porous carrier;
A sulfate of at least one alkaline earth metal supported on the porous carrier,
Forming a catalyst layer having at least a portion of an alkaline earth metal supporting region comprising: and firing the substrate on which the catalyst layer is formed,
,
Here, the step of forming the catalyst layer includes:
The following ingredients:
Inorganic compound particles constituting the porous carrier;
Pt particles or precursors for depositing Pt;
A water-soluble compound of the alkaline earth metal; and an S-containing water-soluble organic compound containing S as a constituent element and capable of forming a sulfate of the alkaline earth metal;
Is mixed with an aqueous solvent to prepare a raw material suspension,
Drying the raw material suspension and further baking to prepare a powder material in which the porous carrier and Pt and a sulfate of an alkaline earth metal are mixed,
Preparing a slurry for forming an alkaline earth metal supporting region containing at least the powder material and an aqueous solvent, and forming the alkaline earth metal supporting region on the base material using the slurry,
A method for producing an exhaust gas purifying catalyst, comprising:
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| EP19868631.3A EP3854478A1 (en) | 2018-10-04 | 2019-09-09 | Exhaust gas purification catalyst |
| US17/276,505 US11821349B2 (en) | 2018-10-04 | 2019-09-09 | Exhaust gas purification catalyst |
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- 2019-09-09 EP EP19868631.3A patent/EP3854478A1/en active Pending
- 2019-09-09 US US17/276,505 patent/US11821349B2/en active Active
- 2019-09-09 CN CN201980065477.9A patent/CN112789107A/en active Pending
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| WO2010137658A1 (en) * | 2009-05-27 | 2010-12-02 | 株式会社 キャタラー | Catalyst for purification of exhaust gas, and process for production thereof |
| WO2010147163A1 (en) * | 2009-06-16 | 2010-12-23 | 株式会社 キャタラー | Exhaust gas purifying catalyst, powder material, and method for producing exhaust gas purifying catalyst |
| WO2011030831A1 (en) * | 2009-09-10 | 2011-03-17 | 株式会社 キャタラー | Catalyst for exhaust gas purification |
| WO2018190300A1 (en) * | 2017-04-11 | 2018-10-18 | 株式会社キャタラー | Catalyst for exhaust gas purification |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| DE102021126689A1 (en) | 2020-10-19 | 2022-04-21 | Cataler Corporation | EMISSION CONTROL DEVICE |
| JP2022066935A (en) * | 2020-10-19 | 2022-05-02 | トヨタ自動車株式会社 | Exhaust gas purification apparatus |
| JP7317787B2 (en) | 2020-10-19 | 2023-07-31 | トヨタ自動車株式会社 | Exhaust gas purifier |
| US11759769B2 (en) | 2020-10-19 | 2023-09-19 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas purification device |
Also Published As
| Publication number | Publication date |
|---|---|
| EP3854478A4 (en) | 2021-07-28 |
| WO2020071059A1 (en) | 2020-04-09 |
| US20210277814A1 (en) | 2021-09-09 |
| US11821349B2 (en) | 2023-11-21 |
| JP6990161B2 (en) | 2022-02-15 |
| EP3854478A1 (en) | 2021-07-28 |
| CN112789107A (en) | 2021-05-11 |
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